General comments

The paper by Wu et al., presents 11 years of meteorological and soil data in a relict permafrost site of the Mahan Mountain on the northeast of the QTP. The paper is generally well organized and clear to me. As a permafrost researcher, I appreciate the considerable efforts taken by the authors to the permafrost community. I also very much welcome the publication of valuable permafrost datasets.

Major comment

1. GST vs LSM: "The ground surface temperature (GST) was measured by the IRP-P at a height of 2 m above the ground surface through non-contact infrared radiation" (P10, L167–168). In this context, the measured value is the radiative skin temperature of the land surface. The surface could be snow, grass, and a mixture of them, right? I would keep the "GST" for soil temperature and "LSM" for ground skin temperature. I hence suggest changing the GST to LSM throughout the manuscript.
2. Permafrost and Active Layer: Based on the authors' title—"Permafrost, active layer and meteorological data (2010–2020) from a relict permafrost site at Mahan Mountain", I would expect the detailed info of permafrost & active layer would be present. However, the paper in its current format is somehow unfocused, and the permafrost/active layer is very lightly discussed and seems equal or even less important than the meteorological data. Hence, I suggest enhancing the statistics of permafrost and active layer conditions and changes during 2010–2020. Since authors have a 11-years' time-series, this could be easily done by 

• adding permafrost temperature profile (MAGT) in different years info into Figure 7, so that readers could see permafrost temperature changes;
• presenting active layer thickness (conditions and changes) based on soil temperature;
• discussing why permafrost could be relict here. This is the most unique feature for this site. The permafrost temperature is very very close to 0°C (i.e., around -0.1°C, and only slightly increased. With the presence of massive ground ice at this site, air temperature warming would mostly lead to significant phase change rather than temperature increase. Also, the thick peat layer and cloudy/foggy weather in summer are favorable for the presence of permafrost. 

     3. Language: The English need to be carefully checked and revised by native speakers.

Specific comments

• P2, L39: The permafrost extent is from Zhang et al., (2000), right? If so, I would only cite the related reference and remove the others here.
• P3, L44: There are "increasing"...
• P4, L98: This is a repeat of L83.
• P5, L111: Relict permafrost will not disappear in the next 40–50 years, this means it is not sensitive to climate warming...
• P10, L166: was ranging → ranged.
• P14, L269--271: Please remove the missing data info in the figure caption as this has already shown well in the Figure. In such a case, the sentence could be much short, i.e. The blank gap stands for the missing data.
• P18, L350: In general, it is difficult to distinguish the permafrost model and LSM, it largely depends on the research purpose.
• Permafrost models, i.e., CryoGRID 3 model (Westermann et al., 2016) has the land surface processes (snow, energy bucket), and permafrost physics have also been implemented into the land surface models, i.e., CLM5, Noah, CLASSIC. What about changing to "...valid models..."? 

Tables & Figures

• Table 1: The operation period is the same for all measured variables, right? In this case, I would suggest removing the column and putting the temporal coverage info in the table caption.
•  Figure 3: Please somehow change the y-axis range of relative humidity (g). A maximum value of 120 is not reasonable here (as you mentioned in L208). A tricky would be to give the y-axis range a little bit greater than 100%, but only show the value labels between 0–100.
• Figure 6
• Should the unit of y-axis be "cm"?

References

Zhang, T., Heginbottom, J. A., Barry, R. G., and Brown, J.: Further Statistics on the Distribution  of Permafrost and Ground Ice in the Northern Hemisphere, Polar Geogr., 24, 14–19,

Westermann, S., Langer, M., Boike, J., Heikenfeld, M., Peter, M., Etzelmüller, B., and Krinner, G.: Simulating the thermal regime and thaw processes of ice-rich permafrost ground with the land-surface model CryoGrid 3, Geosci. Model Dev., 9, 523–546, https://doi.org/10.5194/gmd-9-523-2016, 2016.

As a  staff focusing on model development and application on frozen ground and cold region hydrology, I have read this manuscript with great interest. Permafrost is an indicator of climate change. The response of permafrost to climate change is one of the critical issues in cryospheric science. The 10-year record of permafrost, active layer and meteorological data presented by Tonghua Wu et al. from a relict permafrost site of Mahan Mountain in the northeast of Qinghai-Tibet Plateau is a valuable dataset for permafrost and climate research community, especially important for model developement and validation. This is a clearly written paper and the overall structure of the manuscript is well organized. In my opinion, this manuscript and dataset are an important contribution to permafrost science.Therefore I recommend that the manuscript to be accepted after some minor revisions. And I also look forward to an open access for this dataset as soon as possible after protection period.

Here are my major comments:

1 I strongly suggest to add more detailed temporal variations analysis for active layer hydro-thermal condition and permafrost temperature, particularly for ALT; in addition, the comparison analysis with other permafrost regions is suggested to add.

2 In the introduction section, the authors need to state the particularity of the relict permafrost site at this site, including why permafrost could be relict here.

3 In Figure 5, some low-values of soil moisture occurred in the depth of 40-80cm, and some high-values occurred near 100cm or so, what's the reason?

4 In Figure 7, I suggest to add data sources of topographic base in Figure 1a, and to add unit for DEM in Figure 1b.

5 The language should be polished by English-native-speakers before its acceptance for publication.

As reviewers 1 and 2 stated, I agree that the dataset would be useful for permafrost communities, including general geocryology, permafrost modeling, etc. This manuscript was generally organized well. The observational system is maintained well during the past decade. Besides the comments from reviewers 1 and 2, I also have some further comments.

Major comments

1 - As a data description paper, the authors should make all data descriptions clear and correct. I list a few of the issues here (not limit to these. The authors should read and double-check thoroughly).

• In table 1, air temperature is monitored at two heights (2m and 4m). In Figure 2, the air temperature sensor (the arrow indicated) looks like at 4m height, if the GST sensor is rightly at 2m. In Figure 3a, which one was shown here?
• The authors should note the date of the field picture (during the station was established?). If the surface always looks like this, the observations should be significantly different from the surrounding. Because the vegetation looks different from the surrounding area.
• Figure 3, what temporal resolution is showing here? Hourly, daily, or others?
• For precipitation, I don’t know what mean annual precipitation is (line 186). From Figure 3c, the maximum is < 30mm. I guess they are annual totals?
• Figure 6, y-axis: the unit is meter? Or cm? Why was there an anomaly peak at ~60 (m/cm?) at 9# during Aug 2016 (i.e., Figure 6e)?
• Table 2, range of VWC is 0-100%? Generally, it should be 0-1 because VWC has a unit of m3/m3. Actually, the author did show that in Figure 5.
• Figure 7, was this borehole drilled in 2010? Line 314, the authors stated that the borehole was drilled in Aug 2008. If the borehole was drilled in 2010, the ground temperatures measured in 2010 are not reasonable because of the disturbance of drilling. I also worry about the disturbance of drilling on the records during a couple of years in the beginning. The active layer might return to normal after one year. But the boreholes may not be.
• Figure 7, the horizontal dashed line is 1.2m depth? It significantly departures from the scale (because it looks like at the middle of 0-5m).
• Are the thermistors in the borehole shifting during the monitoring period? Are they calibrated every year or at a constant frequency in lab? Modern sensors and transmitters are electronic devices, and the reference voltage, or signal, may drift over time due to temperature, pressure, or change in ambient conditions.
• Are the depths of all sensors in soil calibrated every year? Because thaw subsidence and frost heaven may have significant influences on the monitoring depths of soil sensors. In other words, after a couple of years, the sensors probably depart significantly from the initial depths.

2 - A confusing point is that long-term MAAT is -1.4 (Line 120) while long-term MAGST is also -1.4 C (Line 171). As I know, generally, MAGST is higher than MAAT (including sites on the Qinghai-Tibetan Plateau, Alaska, and other permafrost sites). But at this site, they look equally. The authors have to explore and explain this feature.

3 - The authors should calculate and explain the thermal offset, i.e., the difference between mean annual soil temperature at the bottom of the active layer and mean annual soil surface (~0cm) temperature (Romanovsky and Osterkamp, 1995). If the values in the manuscript are true, GST is -1.4C and MAGT at 2.4m is ~-0.1C. The offset would be roughly +1.3 C. The authors have to explain such a large reversed thermal offset (because it generally is negative. Of cause, some people (Lin et al., 2015; Luo et al., 2018) ‘found’ small positive offsets).  

4 - References should be appropriate rather than load the manuscript with fancy references (same with the comment from Reviewer 1, however, I would indicate more specifically). An example is Line 39. Boike et al. (2019) only described a site-level dataset (like this manuscript) and gave not any hemispheric summary. Meanwhile, the authors should use terms (permafrost and permafrost region) correctly. Zhang et al. (1999) and Zhang et al. (2000) indicated that permafrost region underlies approximately 22.79 × 10⁶ km² or 23.9% of the exposed land area of the Northern Hemisphere. Certainly, that permafrost may not be present everywhere within permafrost region. They present estimates that indicate that the actual area underlain by permafrost is smaller, ranging approximately from 12.21 to 16.98 × 10⁶ km² (the source of 15 million km²). Whatever, I don’t know how only 15 million km2 can be 24% of the land surface area.

5 - Finally, I totally agree with the comments from Reviewers 1 and 2. The language should be re-edited by English-native-speakers, although it is understandable but need readers to take heavy efforts.

References

Boike, J., Nitzbon, J., Anders, K., Grigoriev, M., Bolshiyanov, D., Langer, M., Lange, S., Bornemann, N., Morgenstern, A., Schreiber, P., Wille, C., Chadburn, S., Gouttevin, I., Burke, E., Kutzbach, L. (2019) A 16-year record (2002–2017) of permafrost, active-layer, and meteorological conditions at the Samoylov Island Arctic permafrost research site, Lena River delta, northern Siberia: an opportunity to validate remote-sensing data and land surface, snow, and permafrost models. Earth Syst. Sci. Data 11, 261-299.

Lin, Z., Burn, C.R., Niu, F., Luo, J., Liu, M., Yin, G. (2015) The Thermal Regime, including a Reversed Thermal Offset, of Arid Permafrost Sites with Variations in Vegetation Cover Density, Wudaoliang Basin, Qinghai-Tibet Plateau. Permafrost and Periglacial Processes 26, 142-159.

Luo, D., Jin, H., Wu, Q., Bense, V.F., He, R., Ma, Q., Gao, S., Jin, X., Lü, L. (2018) Thermal regime of warm-dry permafrost in relation to ground surface temperature in the Source Areas of the Yangtze and Yellow rivers on the Qinghai-Tibet Plateau, SW China. Science of The Total Environment 618, 1033-1045.

Romanovsky, V.E., Osterkamp, T.E. (1995) Interannual variations of the thermal regime of the active layer and near-surface permafrost in northern Alaska. Permafrost and Periglacial Processes 6, 313-335.

Zhang, T., Barry, R.G., Knowles, K., Heginbottom, J.A., Brown, J. (1999) Statistics and characteristics of permafrost and ground‐ice distribution in the Northern Hemisphere. Polar Geography 23, 132-154.

Zhang, T., Heginbottom, J.A., Barry, R.G., Brown, J. (2000) Further statistics on the distribution of permafrost and ground ice in the Northern Hemisphere. Polar Geography 24, 126-131.