Brief communication: Classification of thawed/frozen topsoil state by spectral gradient methods based on SMAP and GCOM-W1 radiometric data

Muzalevskiy, Konstantin; Ruzicka, Zdenek; Roy, Alexandre; Loranty, Michael; Vasiliev, Alexander

doi:https://doi.org/10.5194/egusphere-2022-224

Preprints

https://doi.org/10.5194/egusphere-2022-224

Preprints

06 Jul 2022

| 06 Jul 2022

Brief communication: Classification of thawed/frozen topsoil state by spectral gradient methods based on SMAP and GCOM-W1 radiometric data

Konstantin Muzalevskiy, Zdenek Ruzicka, Alexandre Roy, Michael Loranty, and Alexander Vasiliev

Abstract. From 2015 to 2020, using spectral gradient radiometric methods, the possibility of frozen/thawed state identification of tundra soils was investigated based on SMAP and GCOM-W1 satellite observations of ten test sites located in the Arctic regions of Canada, Finland, Russia, and U.S.. It is shown that the spectral gradients of brightness temperature and reflectivity, measured on the frequency range from 1.4 GHz to 36.5 GHz on horizontal polarization with a determination coefficient from 0.775 to 0.834, root-mean-square-error from 6.6 days to 10.7 days, and bias from -3.4 days to +6.5 days, make it possible to identify the thawed/frozen state of the tundra soils. Spectral gradient methods have a significantly higher accuracy for identification of frozen and thawed state of tundra soils in relation to single-frequency methods based on the calculation of polarization index.

Received: 16 Apr 2022 – Discussion started: 06 Jul 2022

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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Journal article(s) based on this preprint

25 Sep 2023

Brief communication: Identification of tundra topsoil frozen/thawed state from SMAP and GCOM-W1 radiometer measurements using the spectral gradient method

Konstantin Muzalevskiy, Zdenek Ruzicka, Alexandre Roy, Michael Loranty, and Alexander Vasiliev

The Cryosphere, 17, 4155–4164, https://doi.org/10.5194/tc-17-4155-2023,https://doi.org/10.5194/tc-17-4155-2023, 2023

Short summary

Konstantin Muzalevskiy et al.

Interactive discussion

Status: closed

CC1:
'Comment on egusphere-2022-224', Vasiliy Tikhonov, 28 Jul 2022
Dear Editors,
Two months ago the same article by the same authors, but in the Russian language, was received by Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng). As a reviewer, I recommended to reject it (see my review below).
After that the article was sent to two journals: Issledovanie Zemli iz Kosmosa (https://sciencejournals.ru/journal/iszem/, http://www.jizk.ru/) in Russian and The Cryosphere (https://www.the-cryosphere.net/) in English. The Russian journal also rejected the article after a negative review by another reviewer.
I believe the authors violated publication ethics by sending the same article to two journals at the same time.
Kind regards,
Dr. Vasiliy Tikhonov
Senior Scientist
Head of Laboratory for Satellite Monitoring of the Earth's Cryosphere
Department of Earth Research from Space
https://iki.cosmos.ru/research/issledovanie-zemli-iz-kosmosa,
Space Research Institute RAS
https://iki.cosmos.ru/
E-mail: vtikhonov@asp.iki.rssi.ru
vasvlatikh@yandex.com
My review of the article sent to Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng)
The article presents the results of analysis of application of spectroscopic methods for identification of thawed and frozen soil conditions based on brightness temperature measurements by SMAP and GCOM-W1 satellites in the frequency range from 1.4 GHz to 36.5 GHz. The analysis was performed for ten test sites located in the Arctic region in Russia, USA, Canada, and Finland for the period from 2015 to 2020.
The presentation of the material is awful, both the narration and the physics of the problem. There are plenty of trivial or mutually exclusive statements throughout the text. The analysis of the satellite data is done by juggling the values of either brightness temperatures for different channels, or their combinations. The suggested physical interpretations also leave much to be desired.
The first thing I would like to point out is the definitions of "thawed" and "frozen" states of soil, which are absent in the article. Abstract reads: "The data of soil-climatic weather stations at key sites on soil surface temperature at the transition through 0°C were used for ground validation of the thawed/frozen state of soil". I would like to stress that this is fundamentally incorrect, because soil can be thawed at negative temperatures as well (all depends on the soil structure) (see, for example, Ulaby, Long, 2014). Well, let’s leave it to the conscience of the authors. However, at the very end of Results and Discussion (p. 12), Authors report that two sites (SO and SA) were removed from the analysis due to big errors. Authors attribute these errors to
“…unstable soil freezing (soil surface temperature for most of the winter ranged from 0°C to -2°C-4°C according to weather stations)”. So, what is the "frozen" state of the soil, if from 0 to -4°C it is "not frozen"?
Second. The authors determine the effective temperature of soil using the AMSR2 6.9 GHz vertical polarization data. This is allegedly based on the assumption that for this frequency, the AMSR2 sounding angle (55 deg) corresponds to soil Brewster angle. The Authors are probably unaware that the Brewster angle of a soil is determined by its moisture and can vary quite widely (see, e.g., Ulaby, Long, 2014). Hence, it is wrong to arbitrarily assume the 55-degree angle to be the soil Brewster angle. Further, literally the next but one sentence reads: "Further, estimates of ГH(f) will be considered as the apparent values of reflectivity, since the absolute value of TbV(6.9) does not coincide with the actual values of the soil surface temperature Ts0, but is only proportional to them.” Well, is it equal or proportional?! And what kind of physical characteristic is "apparent value of reflectivity"? To whom, how and why is it apparent?!
Third. It is absolutely unclear why the Authors use microwave radiometry data to determine effective soil temperature. There are much more effective methods that use infrared data. At present, methods using satellite microwave radiometry to determine soil temperature are still under development and are not finalized yet. I recommend the Authors the review of Duan et al. (2020) on this topic.
Fourth. The Authors analyze brightness temperature of the test sites obtained by two satellite sensors at different viewing angles: SMAP at 40 degrees and GCOM-W1 at 55 degrees. Thus, there is a comparison of brightness temperatures of different bands received at different angles: band 1.4 GHz at 40 degrees, and bands 6.9 GHz, 10.7 GHz, 18.7 GHz, 36.5 GHz at 55 degrees. And then the conclusion is made about the efficiency of bands 1.4 and 6.9 GHz, and bands 1.4 and 36.5 GHz. The question arises, "Have the authors heard anything about Fresnel formulas?" At different angles, the reflectivity of the same surface is different. The Authors operate with incomparable characteristics.
Fifth. On pages 6-7, Authors derive expression (3) for "isothermal and dielectric-homogeneous half-space." However, on page 10, when discussing Figure 3, namely the spectral gradients of brightness temperature and reflectivity, the Authors explain their highest and lowest values by “a significant contrast of temperatures and permittivities between the shallow and deeper emitting layers of soil". Again, one contradicts the other!
Further the authors engage in formula-juggling, deriving one expression from another. For example, from brightness temperature (with author simplifications) they get surface reflectivity; or from the gradient of brightness temperature spectral density - the gradient of reflectivity. The result is presented in trivial "flip-flop" graphs because one formula follows from the other. In the end, Authors conclude: “Both criteria give comparable accuracies of forecasting thawed and frozen topsoil state for tundra soil cover,” which is bluntly obvious, since one formula is derived from the other.
When considering the gradients of brightness temperature spectral densities and reflectivity “per unit interval of the frequency spectrum”, Authors find that they "seem to be larger for the narrower 1.4-6.98 GHz than for the broader 1.4-36.5 GHz frequency band." There can be no doubt about this, since the discussed characteristics are obtained by dividing by a smaller value (frequency interval) in the first case and a larger value in the second case.
The article is carelessly formatted. There are a number of typos both in the text and in the figure captions. In Figure 4, curve 1 merges in color with curve Ts0.
Also, I would like to draw attention to two more points.
In Introduction (p. 2), when considering various algorithms for determining the thawed and frozen soil states, the Authors mention the polarization index PR as an indicator. In the text, it is said that “The decision on thawed or frozen state of the soil is made when the normalized PR passes through 0.” Based on the expression for PR, it should always be higher than 0, because, for any frequency, the value of brightness temperature on vertical polarization is more than on horizontal. What then does the phrase "…when the normalized PR passes through 0" mean?
The last sentence of Introduction concludes: "Taking into account the development of domestic multifrequency satellite radiometric sensing systems and the expected launch in 2028 of the multispectral (1.4-36.5 GHz) Copernicus Imaging Microwave Radiometer (Kilic et al, 2018) of high spatial resolution (55-5 km), development of new multifrequency radiometric methods to identify thawed/frozen soil state is highly relevant". I wonder, what are these "domestic radiometric multifrequency satellite sensing systems" and why only Copernicus is given as an example, and not some domestic system?
Based on the above, I believe that this article is unacceptable for publication in Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa.
References:
Duan S.-B., Han X.-J., Huang C., Li Z.-L., Wu H., Qian Y., Gao M., Leng P. Land Surface Temperature Retrieval from Passive Microwave Satellite Observations: State-of-the-Art and Future Directions // Remote Sensing. 2020. 12(16), 2573; https://doi.org/10.3390/rs12162573

Ulaby F.T., Long D.G. Microwave Radar and Radiometric Remote Sensing. of Michigan Press. 2014. 984 p
Citation: https://doi.org/10.5194/egusphere-2022-224-CC1
- AC1:
  'Reply on CC1', Konstantin Muzalevskiy, 24 Aug 2022
  
  Response to CC1: 'Comment on egusphere-2022-224', Vasiliy Tikhonov, 28 Jul 2022. https://doi.org/10.5194/egusphere-2022-224-CC1
  Comment 0. Dear Editors,
  
  Two months ago the same article by the same authors, but in the Russian language, was received by Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng). As a reviewer, I recommended to reject it (see my review below).
  
  After that the article was sent to two journals: Issledovanie Zemli iz Kosmosa (https://sciencejournals.ru/journal/iszem/, http://www.jizk.ru/) in Russian and The Cryosphere (https://www.the-cryosphere.net/) in English. The Russian journal also rejected the article after a negative review by another reviewer.
  
  I believe the authors violated publication ethics by sending the same article to two journals at the same time.
  Kind regards,
  
  Dr. Vasiliy Tikhonov
  
  Senior Scientist
  
  Head of Laboratory for Satellite Monitoring of the Earth's Cryosphere
  
  Department of Earth Research from Space
  
  https://iki.cosmos.ru/research/issledovanie-zemli-iz-kosmosa,
  
  Space Research Institute RAS
  
  https://iki.cosmos.ru/
  
  E-mail: vtikhonov@asp.iki.rssi.ru
  
  vasvlatikh@yandex.com
  
  My review of the article sent to Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng)
  Response to comment 0. The persistence with which Vasiliy Tikhonov (PhD) hunts on our manuscript indicates a deep conflict of interests of Vasiliy Tikhonov (PhD) likely not only with the subject of our work, but with the first author.
  
  The official license agreement filled out by the editors of "Issledovanie Zemli iz Kosmosa", and sent to me was not signed by me on purpose, because I submitted the manuscript to The Cryosphere. For this reason, I did not give legal obligations not to publish the article in other journals and did not give the right to publish our article in the journal "Issledovanie Zemli iz Kosmosa".
  The submitted manuscript to The Cryosphere is a continuation of our research. (This is the third article in our research cycle). The Russian version of this article was rejected by the journal “Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa” in 2022 based on a single expert decision (without the possibility respond to reviewer comments). The second article from our series was submitted to the journal “Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa” last year (03/02/2021) and it also was rejected. However, later, with almost no changes in the main content, the second article in our series was successfully reviewed and published in (Muzalevskiy et al., 2021). The first article in our series was published in (Muzalevskiy and Ruzicka, 2020).
  Reference
  
  Muzalevskiy K., Ruzicka Z., Roy A., Loranty M., Vasiliev A. Classification of the frozen/thawed surface state of Northern land areas based on SMAP and GCOM-W1 brightness temperature observations at 1.4 GHz and 6.9 GHz. Remote Sensing Letters. 2021. Vol. 12. No. 11. P. 1073-1081. 10.1080/2150704X.2021.1963497
  
  Muzalevskiy K., Ruzicka Z. Detection of soil freeze/thaw states in the Arctic region based on combined SMAP and AMSR-2 radio brightness observations // International Journal of Remote Sensing. – 2020. – V. 41.- Is. 14. – P. 5046-5061. DOI: 10.1080/01431161.2020.1724348.
  I would like to have more objective assessment of our work by independent experts, and not only Vasiliy Tikhonov (PhD).
  
  I have responded on behalf of all the authors to all comments Vasiliy Tikhonov (PhD), most of which are written in disrespectful, aggressive and peremptory form. Response to the comments are contained in the attached file.
  Best regards,
  
  Muzalevskiy Konstantin (PhD)
  
  Head of Laboratory of Radiophysics of the Earth Remote Sensing,
  
  Kirensky Institute of Physics,
  
  Federal Research Center KSC Siberian Branch RAS
  
  Citation: https://doi.org/10.5194/egusphere-2022-224-AC1
  - CC2: 'Reply on AC1', Vasiliy Tikhonov, 05 Sep 2022
    
    Dear Editors,
    In contrast to the authors of the article, I will be brief.
    I do not and will not chase the article out of publication. I have no conflict of interest with either the topic of the article or the first author. My research is not directly related to the topic of the article and I met the first author just once and for a very short time.
    It happened so that this article, though in Russian, was sent to me for review from Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng). I received it on April 8, 2022. On May 14, 2022, I sent a negative review to the editors and recommended to rejected it. It is the editorial board of the journal that decides whether to publish an article or not and I am not a member of it. The article was rejected by the journal’s editorial board. In my previous comments, I cited my review of the Russian version of the article (translated into English) to show that both versions are the same, but written in different languages (Russian and English), and also to show my attitude to the presented material. The authors decided to respond to my comments and did so in great detail. However, their answers are not satisfactory: a lot of text and reasoning and almost no specific answers to my comments. This time I am not a reviewer of the article and I have neither desire nor time to continue the discussion. I believe the actual reviewers of the article and the Editors of The Cryosphere will make a right decision on its fate.
    On June 26, 2022, I received the same article (in Russian) for review from Issledovaniya Zemli Is Kosmosa (https://sciencejournals.ru/journal/iszem/). I declined reviewing as I had already reviewed it. On June 28, 2022, the journal sent the article to another reviewer who sent his review back to the journal on July 7. Then the authors withdrew the article from that journal.
    The rules for authors of Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa state that "Only high-quality original research work, not published previously and not under review with another journal, is accepted for publication" (http://jr.rse.cosmos.ru/default.aspx?id=5&lang=eng). The Cryosphere’s Obligations for authors include Paragraph 7 with a similar requirement (https://www.the-cryosphere.net/policies/obligations_for_authors.html). As far as I know, Issledovaniya Zemli Is Kosmosa adheres to the same rules.
    Now let us have a look at the dates of submission of the article to different journals. The article page (https://egusphere.copernicus.org/preprints/2022/egusphere-2022-224/) shows that it was submitted to The Cryosphere on April 16, 2022, and opened for discussion on July 6, 2022. Thus, while under review in The Cryosphere, the article was submitted to two other journals, first, to Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa (my negative review is dated May 14) and, second, to Issledovaniya Zemli Is Kosmosa (no later than June 26, 2022, when I declined reviewing). In addition, the review for Issledovaniya Zemli Is Kosmosa was not sent to the journal until July 7, 2022. At that time the article was already under discussion in The Cryosphere.
    Evidently, the authors violated publication ethics twice. I don’t know how the Editors of The Cryosphere treat this fact, but I’m aware that the two Russian journals above strive to enforce publication ethics in full.
    
    Kind regards,
    Dr. Vasiliy Tikhonov
    Senior Scientist
    Head of Laboratory for Satellite Monitoring of the Earth's Cryosphere
    Department of Earth Research from Space https://iki.cosmos.ru/research/issledovanie-zemli-iz-kosmosa,
    Space Research Institute RAS https://iki.cosmos.ru/
    E-mail: vtikhonov@asp.iki.rssi.ru , vasvlatikh@yandex.ru
    
    Citation: https://doi.org/10.5194/egusphere-2022-224-CC2
    
    AC2: 'Reply on CC2', Konstantin Muzalevskiy, 13 Sep 2022
    
    Response to CC2: 'Reply on AC1', Vasiliy Tikhonov, 05 Sep 2022 '.
    
    https://doi.org/10.5194/egusphere-2022-224-CC2
    
    Comment 1.
    Dear Editors,
    In contrast to the authors of the article, I will be brief.
    I do not and will not chase the article out of publication. I have no conflict of interest with either the topic of the article or the first author. My research is not directly related to the topic of the article and I met the first author just once and for a very short time.
    It happened so that this article, though in Russian, was sent to me for review from Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng). I received it on April 8, 2022. On May 14, 2022, I sent a negative review to the editors and recommended to rejected it. It is the editorial board of the journal that decides whether to publish an article or not and I am not a member of it. The article was rejected by the journal’s editorial board. In my previous comments, I cited my review of the Russian version of the article (translated into English) to show that both versions are the same, but written in different languages (Russian and English), and also to show my attitude to the presented material. The authors decided to respond to my comments and did so in great detail. However, their answers are not satisfactory: a lot of text and reasoning and almost no specific answers to my comments. This time I am not a reviewer of the article and I have neither desire nor time to continue the discussion. I believe the actual reviewers of the article and the Editors of The Cryosphere will make a right decision on its fate.
    On June 26, 2022, I received the same article (in Russian) for review from Issledovaniya Zemli Is Kosmosa (https://sciencejournals.ru/journal/iszem/). I declined reviewing as I had already reviewed it. On June 28, 2022, the journal sent the article to another reviewer who sent his review back to the journal on July 7. Then the authors withdrew the article from that journal.
    The rules for authors of Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa state that "Only high-quality original research work, not published previously and not under review with another journal, is accepted for publication" (http://jr.rse.cosmos.ru/default.aspx?id=5&lang=eng). The Cryosphere’s Obligations for authors include Paragraph 7 with a similar requirement (https://www.the-cryosphere.net/policies/obligations_for_authors.html). As far as I know, Issledovaniya Zemli Is Kosmosa adheres to the same rules.
    Now let us have a look at the dates of submission of the article to different journals. The article page (https://egusphere.copernicus.org/preprints/2022/egusphere-2022-224/) shows that it was submitted to The Cryosphere on April 16, 2022, and opened for discussion on July 6, 2022. Thus, while under review in The Cryosphere, the article was submitted to two other journals, first, to Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa (my negative review is dated May 14) and, second, to Issledovaniya Zemli Is Kosmosa (no later than June 26, 2022, when I declined reviewing). In addition, the review for Issledovaniya Zemli Is Kosmosa was not sent to the journal until July 7, 2022. At that time the article was already under discussion in The Cryosphere.
    Evidently, the authors violated publication ethics twice. I don’t know how the Editors of The Cryosphere treat this fact, but I’m aware that the two Russian journals above strive to enforce publication ethics in full.
    
    Kind regards,
    Dr. Vasiliy Tikhonov
    Senior Scientist
    Head of Laboratory for Satellite Monitoring of the Earth's Cryosphere
    Department of Earth Research from Space https://iki.cosmos.ru/research/issledovanie-zemli-iz-kosmosa,
    Space Research Institute RAS https://iki.cosmos.ru/
    E-mail: vtikhonov@asp.iki.rssi.ru , vasvlatikh@yandex.ru
    
    Response to comment 1: I have already given a detailed answer to this speculation made by Vasiliy Tikhonov (see https://doi.org/10.5194/egusphere-2022-224-AC1. Response to comment 0).
    The persistence with which Vasiliy Tikhonov hunts on our manuscript
    
    indicates a deep conflict of interests of Vasiliy Tikhonov likely not only with the subject of our
    
    work, but with the first author. I would like to have more objective assessment of our work by independent experts, and not only Vasiliy
    
    Tikhonov (PhD).
    
    Best regards,
    
    Muzalevskiy Konstantin (PhD)
    
    Head of Laboratory of Radiophysics of the Earth Remote Sensing,
    
    Kirensky Institute of Physics,
    
    Federal Research Center KSC Siberian Branch RAS
    
    Citation: https://doi.org/10.5194/egusphere-2022-224-AC2
RC1:
'Comment on egusphere-2022-224', Anonymous Referee #1, 16 Sep 2022
I believe this is an interesting manuscript, which will contribute to the literature on freeze/thaw classification. However, I do believe revisions are necessary before publication. I noted some more detailed points below, but in summary I believe that some additional discussions on the frequencies/angles used, and the inclusion of the other study sites as well as some discussion on the differences between the sites and the impact of this on the results would be critical.

Major comments:

Line 98: “The difference in observation angles 40° and 55°, respectively for SMAP and AMSR2, was neglected.”: why was this neglected, and what is the justification. As far as I could tell, there is no discussion on this in section 4. I believe a thorough discussion of this is necessary as this is at the basis of this methodology.

Figure 1: Only Happy Valley test site is shown. I would argue its critical to somehow show the other test sites as well. At the very least there should be an example of one of the sites where the methodology does not work as well according to the authors.

In section 2, the authors describe differences and similarities between the test sites. I can not see any discussion on how those conditions influence the outcome except for ‘surface water area’ which is briefly discussed but not with a focus on the differences between test sites. Please elaborate in the discussion section the soundness of the results for those different sites as it speaks to the transferability of your approach.

Line 122: “The physical basis for this effect is the observation angle of the AMSR-2 radiometer of GCOM-W1 satellite, which is close to the Brewster angle (55º)”: please provide a citation(s) for this paragraph.

Line 181-182: Does this mean that this method is not applicable in lower latitudes/sub Arctic regions? Please expand/clarify.

Minor comments:

There are several spelling/grammar mistakes. I noted some below, there may be others that I have not found.

Line 134: ovals are not visible possibly replace with vertical line with a stronger color/stronger line width

Figure 3: Figure caption to long, difficult to get the essential points from it. Please shorten. Also, it should be made clear in the figure caption that the different colors represent the different test sites.

Line 188: swap identification with identify

Line 198: “FT topsoil state identification possible with determination coefficient”: missing ‘is’

The word ‘region’ is used several times incorrectly in my opinion. Specifically, line 138 where it should be replaced by ‘time period’ or something similar.
Citation: https://doi.org/10.5194/egusphere-2022-224-RC1
- AC4: 'Reply on RC1', Konstantin Muzalevskiy, 23 Dec 2022
  
  Dear, reviewer,
  Thank you very much, for your opinion and support. My responses to you comments are given in the attached file.
  Best regards, Muzalevskiy Konstantin
  
  Citation: https://doi.org/10.5194/egusphere-2022-224-AC4
RC2:
'Comment on egusphere-2022-224', Anonymous Referee #2, 18 Nov 2022

In my opinion this manuscript communicates an interesting and potentially important observation that the spectral gradients of brightness temperatures can be used to detect the freezing / thawing of soil. I also think that the paper is well written. I do have a couple of more specific comments:

-Line 30: the authors say that the single frequency methods use viewing angle of about 40 degrees. At least in case of SMOS also multiangular data is available even though the authors mentioned in the introduction might not have used it.

-Lines 133-134, Fig. 1: the ovals mentioned in the text are practically invisible in Fig. 1 and their visibility must be improved.

-Fig. 2: the color of Ts0 and first gradient pair is very hard to distinguish. A different set of colors or line types should be applied.

-Line 175-: If the soil is dry the penetration depth at 1.4 GHz is couple of centimeters. Have the authors considered that the difference between using 6.9-1.4 GHz and 36.5-1.4 GHz could be related to this?

Citation: https://doi.org/10.5194/egusphere-2022-224-RC2
- AC3: 'Reply on RC2', Konstantin Muzalevskiy, 16 Dec 2022
  
  Dear, reviewer,
  Thank you very much, for your opinion and support. Your and RC1 feedback gave me back the ground under my feet and the possibility of further work on the article. My responses to you comments are given in the attached file.
  Best regards, Muzalevskiy Konstantin
  
  Citation: https://doi.org/10.5194/egusphere-2022-224-AC3

Interactive discussion

Status: closed

CC1:
'Comment on egusphere-2022-224', Vasiliy Tikhonov, 28 Jul 2022
Dear Editors,
Two months ago the same article by the same authors, but in the Russian language, was received by Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng). As a reviewer, I recommended to reject it (see my review below).
After that the article was sent to two journals: Issledovanie Zemli iz Kosmosa (https://sciencejournals.ru/journal/iszem/, http://www.jizk.ru/) in Russian and The Cryosphere (https://www.the-cryosphere.net/) in English. The Russian journal also rejected the article after a negative review by another reviewer.
I believe the authors violated publication ethics by sending the same article to two journals at the same time.
Kind regards,
Dr. Vasiliy Tikhonov
Senior Scientist
Head of Laboratory for Satellite Monitoring of the Earth's Cryosphere
Department of Earth Research from Space
https://iki.cosmos.ru/research/issledovanie-zemli-iz-kosmosa,
Space Research Institute RAS
https://iki.cosmos.ru/
E-mail: vtikhonov@asp.iki.rssi.ru
vasvlatikh@yandex.com
My review of the article sent to Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng)
The article presents the results of analysis of application of spectroscopic methods for identification of thawed and frozen soil conditions based on brightness temperature measurements by SMAP and GCOM-W1 satellites in the frequency range from 1.4 GHz to 36.5 GHz. The analysis was performed for ten test sites located in the Arctic region in Russia, USA, Canada, and Finland for the period from 2015 to 2020.
The presentation of the material is awful, both the narration and the physics of the problem. There are plenty of trivial or mutually exclusive statements throughout the text. The analysis of the satellite data is done by juggling the values of either brightness temperatures for different channels, or their combinations. The suggested physical interpretations also leave much to be desired.
The first thing I would like to point out is the definitions of "thawed" and "frozen" states of soil, which are absent in the article. Abstract reads: "The data of soil-climatic weather stations at key sites on soil surface temperature at the transition through 0°C were used for ground validation of the thawed/frozen state of soil". I would like to stress that this is fundamentally incorrect, because soil can be thawed at negative temperatures as well (all depends on the soil structure) (see, for example, Ulaby, Long, 2014). Well, let’s leave it to the conscience of the authors. However, at the very end of Results and Discussion (p. 12), Authors report that two sites (SO and SA) were removed from the analysis due to big errors. Authors attribute these errors to
“…unstable soil freezing (soil surface temperature for most of the winter ranged from 0°C to -2°C-4°C according to weather stations)”. So, what is the "frozen" state of the soil, if from 0 to -4°C it is "not frozen"?
Second. The authors determine the effective temperature of soil using the AMSR2 6.9 GHz vertical polarization data. This is allegedly based on the assumption that for this frequency, the AMSR2 sounding angle (55 deg) corresponds to soil Brewster angle. The Authors are probably unaware that the Brewster angle of a soil is determined by its moisture and can vary quite widely (see, e.g., Ulaby, Long, 2014). Hence, it is wrong to arbitrarily assume the 55-degree angle to be the soil Brewster angle. Further, literally the next but one sentence reads: "Further, estimates of ГH(f) will be considered as the apparent values of reflectivity, since the absolute value of TbV(6.9) does not coincide with the actual values of the soil surface temperature Ts0, but is only proportional to them.” Well, is it equal or proportional?! And what kind of physical characteristic is "apparent value of reflectivity"? To whom, how and why is it apparent?!
Third. It is absolutely unclear why the Authors use microwave radiometry data to determine effective soil temperature. There are much more effective methods that use infrared data. At present, methods using satellite microwave radiometry to determine soil temperature are still under development and are not finalized yet. I recommend the Authors the review of Duan et al. (2020) on this topic.
Fourth. The Authors analyze brightness temperature of the test sites obtained by two satellite sensors at different viewing angles: SMAP at 40 degrees and GCOM-W1 at 55 degrees. Thus, there is a comparison of brightness temperatures of different bands received at different angles: band 1.4 GHz at 40 degrees, and bands 6.9 GHz, 10.7 GHz, 18.7 GHz, 36.5 GHz at 55 degrees. And then the conclusion is made about the efficiency of bands 1.4 and 6.9 GHz, and bands 1.4 and 36.5 GHz. The question arises, "Have the authors heard anything about Fresnel formulas?" At different angles, the reflectivity of the same surface is different. The Authors operate with incomparable characteristics.
Fifth. On pages 6-7, Authors derive expression (3) for "isothermal and dielectric-homogeneous half-space." However, on page 10, when discussing Figure 3, namely the spectral gradients of brightness temperature and reflectivity, the Authors explain their highest and lowest values by “a significant contrast of temperatures and permittivities between the shallow and deeper emitting layers of soil". Again, one contradicts the other!
Further the authors engage in formula-juggling, deriving one expression from another. For example, from brightness temperature (with author simplifications) they get surface reflectivity; or from the gradient of brightness temperature spectral density - the gradient of reflectivity. The result is presented in trivial "flip-flop" graphs because one formula follows from the other. In the end, Authors conclude: “Both criteria give comparable accuracies of forecasting thawed and frozen topsoil state for tundra soil cover,” which is bluntly obvious, since one formula is derived from the other.
When considering the gradients of brightness temperature spectral densities and reflectivity “per unit interval of the frequency spectrum”, Authors find that they "seem to be larger for the narrower 1.4-6.98 GHz than for the broader 1.4-36.5 GHz frequency band." There can be no doubt about this, since the discussed characteristics are obtained by dividing by a smaller value (frequency interval) in the first case and a larger value in the second case.
The article is carelessly formatted. There are a number of typos both in the text and in the figure captions. In Figure 4, curve 1 merges in color with curve Ts0.
Also, I would like to draw attention to two more points.
In Introduction (p. 2), when considering various algorithms for determining the thawed and frozen soil states, the Authors mention the polarization index PR as an indicator. In the text, it is said that “The decision on thawed or frozen state of the soil is made when the normalized PR passes through 0.” Based on the expression for PR, it should always be higher than 0, because, for any frequency, the value of brightness temperature on vertical polarization is more than on horizontal. What then does the phrase "…when the normalized PR passes through 0" mean?
The last sentence of Introduction concludes: "Taking into account the development of domestic multifrequency satellite radiometric sensing systems and the expected launch in 2028 of the multispectral (1.4-36.5 GHz) Copernicus Imaging Microwave Radiometer (Kilic et al, 2018) of high spatial resolution (55-5 km), development of new multifrequency radiometric methods to identify thawed/frozen soil state is highly relevant". I wonder, what are these "domestic radiometric multifrequency satellite sensing systems" and why only Copernicus is given as an example, and not some domestic system?
Based on the above, I believe that this article is unacceptable for publication in Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa.
References:
Duan S.-B., Han X.-J., Huang C., Li Z.-L., Wu H., Qian Y., Gao M., Leng P. Land Surface Temperature Retrieval from Passive Microwave Satellite Observations: State-of-the-Art and Future Directions // Remote Sensing. 2020. 12(16), 2573; https://doi.org/10.3390/rs12162573

Ulaby F.T., Long D.G. Microwave Radar and Radiometric Remote Sensing. of Michigan Press. 2014. 984 p
Citation: https://doi.org/10.5194/egusphere-2022-224-CC1
- AC1:
  'Reply on CC1', Konstantin Muzalevskiy, 24 Aug 2022
  
  Response to CC1: 'Comment on egusphere-2022-224', Vasiliy Tikhonov, 28 Jul 2022. https://doi.org/10.5194/egusphere-2022-224-CC1
  Comment 0. Dear Editors,
  
  Two months ago the same article by the same authors, but in the Russian language, was received by Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng). As a reviewer, I recommended to reject it (see my review below).
  
  After that the article was sent to two journals: Issledovanie Zemli iz Kosmosa (https://sciencejournals.ru/journal/iszem/, http://www.jizk.ru/) in Russian and The Cryosphere (https://www.the-cryosphere.net/) in English. The Russian journal also rejected the article after a negative review by another reviewer.
  
  I believe the authors violated publication ethics by sending the same article to two journals at the same time.
  Kind regards,
  
  Dr. Vasiliy Tikhonov
  
  Senior Scientist
  
  Head of Laboratory for Satellite Monitoring of the Earth's Cryosphere
  
  Department of Earth Research from Space
  
  https://iki.cosmos.ru/research/issledovanie-zemli-iz-kosmosa,
  
  Space Research Institute RAS
  
  https://iki.cosmos.ru/
  
  E-mail: vtikhonov@asp.iki.rssi.ru
  
  vasvlatikh@yandex.com
  
  My review of the article sent to Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng)
  Response to comment 0. The persistence with which Vasiliy Tikhonov (PhD) hunts on our manuscript indicates a deep conflict of interests of Vasiliy Tikhonov (PhD) likely not only with the subject of our work, but with the first author.
  
  The official license agreement filled out by the editors of "Issledovanie Zemli iz Kosmosa", and sent to me was not signed by me on purpose, because I submitted the manuscript to The Cryosphere. For this reason, I did not give legal obligations not to publish the article in other journals and did not give the right to publish our article in the journal "Issledovanie Zemli iz Kosmosa".
  The submitted manuscript to The Cryosphere is a continuation of our research. (This is the third article in our research cycle). The Russian version of this article was rejected by the journal “Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa” in 2022 based on a single expert decision (without the possibility respond to reviewer comments). The second article from our series was submitted to the journal “Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa” last year (03/02/2021) and it also was rejected. However, later, with almost no changes in the main content, the second article in our series was successfully reviewed and published in (Muzalevskiy et al., 2021). The first article in our series was published in (Muzalevskiy and Ruzicka, 2020).
  Reference
  
  Muzalevskiy K., Ruzicka Z., Roy A., Loranty M., Vasiliev A. Classification of the frozen/thawed surface state of Northern land areas based on SMAP and GCOM-W1 brightness temperature observations at 1.4 GHz and 6.9 GHz. Remote Sensing Letters. 2021. Vol. 12. No. 11. P. 1073-1081. 10.1080/2150704X.2021.1963497
  
  Muzalevskiy K., Ruzicka Z. Detection of soil freeze/thaw states in the Arctic region based on combined SMAP and AMSR-2 radio brightness observations // International Journal of Remote Sensing. – 2020. – V. 41.- Is. 14. – P. 5046-5061. DOI: 10.1080/01431161.2020.1724348.
  I would like to have more objective assessment of our work by independent experts, and not only Vasiliy Tikhonov (PhD).
  
  I have responded on behalf of all the authors to all comments Vasiliy Tikhonov (PhD), most of which are written in disrespectful, aggressive and peremptory form. Response to the comments are contained in the attached file.
  Best regards,
  
  Muzalevskiy Konstantin (PhD)
  
  Head of Laboratory of Radiophysics of the Earth Remote Sensing,
  
  Kirensky Institute of Physics,
  
  Federal Research Center KSC Siberian Branch RAS
  
  Citation: https://doi.org/10.5194/egusphere-2022-224-AC1
  - CC2: 'Reply on AC1', Vasiliy Tikhonov, 05 Sep 2022
    
    Dear Editors,
    In contrast to the authors of the article, I will be brief.
    I do not and will not chase the article out of publication. I have no conflict of interest with either the topic of the article or the first author. My research is not directly related to the topic of the article and I met the first author just once and for a very short time.
    It happened so that this article, though in Russian, was sent to me for review from Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng). I received it on April 8, 2022. On May 14, 2022, I sent a negative review to the editors and recommended to rejected it. It is the editorial board of the journal that decides whether to publish an article or not and I am not a member of it. The article was rejected by the journal’s editorial board. In my previous comments, I cited my review of the Russian version of the article (translated into English) to show that both versions are the same, but written in different languages (Russian and English), and also to show my attitude to the presented material. The authors decided to respond to my comments and did so in great detail. However, their answers are not satisfactory: a lot of text and reasoning and almost no specific answers to my comments. This time I am not a reviewer of the article and I have neither desire nor time to continue the discussion. I believe the actual reviewers of the article and the Editors of The Cryosphere will make a right decision on its fate.
    On June 26, 2022, I received the same article (in Russian) for review from Issledovaniya Zemli Is Kosmosa (https://sciencejournals.ru/journal/iszem/). I declined reviewing as I had already reviewed it. On June 28, 2022, the journal sent the article to another reviewer who sent his review back to the journal on July 7. Then the authors withdrew the article from that journal.
    The rules for authors of Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa state that "Only high-quality original research work, not published previously and not under review with another journal, is accepted for publication" (http://jr.rse.cosmos.ru/default.aspx?id=5&lang=eng). The Cryosphere’s Obligations for authors include Paragraph 7 with a similar requirement (https://www.the-cryosphere.net/policies/obligations_for_authors.html). As far as I know, Issledovaniya Zemli Is Kosmosa adheres to the same rules.
    Now let us have a look at the dates of submission of the article to different journals. The article page (https://egusphere.copernicus.org/preprints/2022/egusphere-2022-224/) shows that it was submitted to The Cryosphere on April 16, 2022, and opened for discussion on July 6, 2022. Thus, while under review in The Cryosphere, the article was submitted to two other journals, first, to Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa (my negative review is dated May 14) and, second, to Issledovaniya Zemli Is Kosmosa (no later than June 26, 2022, when I declined reviewing). In addition, the review for Issledovaniya Zemli Is Kosmosa was not sent to the journal until July 7, 2022. At that time the article was already under discussion in The Cryosphere.
    Evidently, the authors violated publication ethics twice. I don’t know how the Editors of The Cryosphere treat this fact, but I’m aware that the two Russian journals above strive to enforce publication ethics in full.
    
    Kind regards,
    Dr. Vasiliy Tikhonov
    Senior Scientist
    Head of Laboratory for Satellite Monitoring of the Earth's Cryosphere
    Department of Earth Research from Space https://iki.cosmos.ru/research/issledovanie-zemli-iz-kosmosa,
    Space Research Institute RAS https://iki.cosmos.ru/
    E-mail: vtikhonov@asp.iki.rssi.ru , vasvlatikh@yandex.ru
    
    Citation: https://doi.org/10.5194/egusphere-2022-224-CC2
    
    AC2: 'Reply on CC2', Konstantin Muzalevskiy, 13 Sep 2022
    
    Response to CC2: 'Reply on AC1', Vasiliy Tikhonov, 05 Sep 2022 '.
    
    https://doi.org/10.5194/egusphere-2022-224-CC2
    
    Comment 1.
    Dear Editors,
    In contrast to the authors of the article, I will be brief.
    I do not and will not chase the article out of publication. I have no conflict of interest with either the topic of the article or the first author. My research is not directly related to the topic of the article and I met the first author just once and for a very short time.
    It happened so that this article, though in Russian, was sent to me for review from Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa (http://jr.rse.cosmos.ru/?lang=eng). I received it on April 8, 2022. On May 14, 2022, I sent a negative review to the editors and recommended to rejected it. It is the editorial board of the journal that decides whether to publish an article or not and I am not a member of it. The article was rejected by the journal’s editorial board. In my previous comments, I cited my review of the Russian version of the article (translated into English) to show that both versions are the same, but written in different languages (Russian and English), and also to show my attitude to the presented material. The authors decided to respond to my comments and did so in great detail. However, their answers are not satisfactory: a lot of text and reasoning and almost no specific answers to my comments. This time I am not a reviewer of the article and I have neither desire nor time to continue the discussion. I believe the actual reviewers of the article and the Editors of The Cryosphere will make a right decision on its fate.
    On June 26, 2022, I received the same article (in Russian) for review from Issledovaniya Zemli Is Kosmosa (https://sciencejournals.ru/journal/iszem/). I declined reviewing as I had already reviewed it. On June 28, 2022, the journal sent the article to another reviewer who sent his review back to the journal on July 7. Then the authors withdrew the article from that journal.
    The rules for authors of Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa state that "Only high-quality original research work, not published previously and not under review with another journal, is accepted for publication" (http://jr.rse.cosmos.ru/default.aspx?id=5&lang=eng). The Cryosphere’s Obligations for authors include Paragraph 7 with a similar requirement (https://www.the-cryosphere.net/policies/obligations_for_authors.html). As far as I know, Issledovaniya Zemli Is Kosmosa adheres to the same rules.
    Now let us have a look at the dates of submission of the article to different journals. The article page (https://egusphere.copernicus.org/preprints/2022/egusphere-2022-224/) shows that it was submitted to The Cryosphere on April 16, 2022, and opened for discussion on July 6, 2022. Thus, while under review in The Cryosphere, the article was submitted to two other journals, first, to Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli Iz Kosmosa (my negative review is dated May 14) and, second, to Issledovaniya Zemli Is Kosmosa (no later than June 26, 2022, when I declined reviewing). In addition, the review for Issledovaniya Zemli Is Kosmosa was not sent to the journal until July 7, 2022. At that time the article was already under discussion in The Cryosphere.
    Evidently, the authors violated publication ethics twice. I don’t know how the Editors of The Cryosphere treat this fact, but I’m aware that the two Russian journals above strive to enforce publication ethics in full.
    
    Kind regards,
    Dr. Vasiliy Tikhonov
    Senior Scientist
    Head of Laboratory for Satellite Monitoring of the Earth's Cryosphere
    Department of Earth Research from Space https://iki.cosmos.ru/research/issledovanie-zemli-iz-kosmosa,
    Space Research Institute RAS https://iki.cosmos.ru/
    E-mail: vtikhonov@asp.iki.rssi.ru , vasvlatikh@yandex.ru
    
    Response to comment 1: I have already given a detailed answer to this speculation made by Vasiliy Tikhonov (see https://doi.org/10.5194/egusphere-2022-224-AC1. Response to comment 0).
    The persistence with which Vasiliy Tikhonov hunts on our manuscript
    
    indicates a deep conflict of interests of Vasiliy Tikhonov likely not only with the subject of our
    
    work, but with the first author. I would like to have more objective assessment of our work by independent experts, and not only Vasiliy
    
    Tikhonov (PhD).
    
    Best regards,
    
    Muzalevskiy Konstantin (PhD)
    
    Head of Laboratory of Radiophysics of the Earth Remote Sensing,
    
    Kirensky Institute of Physics,
    
    Federal Research Center KSC Siberian Branch RAS
    
    Citation: https://doi.org/10.5194/egusphere-2022-224-AC2
RC1:
'Comment on egusphere-2022-224', Anonymous Referee #1, 16 Sep 2022
I believe this is an interesting manuscript, which will contribute to the literature on freeze/thaw classification. However, I do believe revisions are necessary before publication. I noted some more detailed points below, but in summary I believe that some additional discussions on the frequencies/angles used, and the inclusion of the other study sites as well as some discussion on the differences between the sites and the impact of this on the results would be critical.

Major comments:

Line 98: “The difference in observation angles 40° and 55°, respectively for SMAP and AMSR2, was neglected.”: why was this neglected, and what is the justification. As far as I could tell, there is no discussion on this in section 4. I believe a thorough discussion of this is necessary as this is at the basis of this methodology.

Figure 1: Only Happy Valley test site is shown. I would argue its critical to somehow show the other test sites as well. At the very least there should be an example of one of the sites where the methodology does not work as well according to the authors.

In section 2, the authors describe differences and similarities between the test sites. I can not see any discussion on how those conditions influence the outcome except for ‘surface water area’ which is briefly discussed but not with a focus on the differences between test sites. Please elaborate in the discussion section the soundness of the results for those different sites as it speaks to the transferability of your approach.

Line 122: “The physical basis for this effect is the observation angle of the AMSR-2 radiometer of GCOM-W1 satellite, which is close to the Brewster angle (55º)”: please provide a citation(s) for this paragraph.

Line 181-182: Does this mean that this method is not applicable in lower latitudes/sub Arctic regions? Please expand/clarify.

Minor comments:

There are several spelling/grammar mistakes. I noted some below, there may be others that I have not found.

Line 134: ovals are not visible possibly replace with vertical line with a stronger color/stronger line width

Figure 3: Figure caption to long, difficult to get the essential points from it. Please shorten. Also, it should be made clear in the figure caption that the different colors represent the different test sites.

Line 188: swap identification with identify

Line 198: “FT topsoil state identification possible with determination coefficient”: missing ‘is’

The word ‘region’ is used several times incorrectly in my opinion. Specifically, line 138 where it should be replaced by ‘time period’ or something similar.
Citation: https://doi.org/10.5194/egusphere-2022-224-RC1
- AC4: 'Reply on RC1', Konstantin Muzalevskiy, 23 Dec 2022
  
  Dear, reviewer,
  Thank you very much, for your opinion and support. My responses to you comments are given in the attached file.
  Best regards, Muzalevskiy Konstantin
  
  Citation: https://doi.org/10.5194/egusphere-2022-224-AC4
RC2:
'Comment on egusphere-2022-224', Anonymous Referee #2, 18 Nov 2022

In my opinion this manuscript communicates an interesting and potentially important observation that the spectral gradients of brightness temperatures can be used to detect the freezing / thawing of soil. I also think that the paper is well written. I do have a couple of more specific comments:

-Line 30: the authors say that the single frequency methods use viewing angle of about 40 degrees. At least in case of SMOS also multiangular data is available even though the authors mentioned in the introduction might not have used it.

-Lines 133-134, Fig. 1: the ovals mentioned in the text are practically invisible in Fig. 1 and their visibility must be improved.

-Fig. 2: the color of Ts0 and first gradient pair is very hard to distinguish. A different set of colors or line types should be applied.

-Line 175-: If the soil is dry the penetration depth at 1.4 GHz is couple of centimeters. Have the authors considered that the difference between using 6.9-1.4 GHz and 36.5-1.4 GHz could be related to this?

Citation: https://doi.org/10.5194/egusphere-2022-224-RC2
- AC3: 'Reply on RC2', Konstantin Muzalevskiy, 16 Dec 2022
  
  Dear, reviewer,
  Thank you very much, for your opinion and support. Your and RC1 feedback gave me back the ground under my feet and the possibility of further work on the article. My responses to you comments are given in the attached file.
  Best regards, Muzalevskiy Konstantin
  
  Citation: https://doi.org/10.5194/egusphere-2022-224-AC3

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Publish subject to minor revisions (review by editor) (23 Jul 2023) by Christian Beer

AR by Konstantin Muzalevskiy on behalf of the Authors (27 Jul 2023) Author's response Author's tracked changes Manuscript

ED: Publish as is (09 Aug 2023) by Christian Beer

AR by Konstantin Muzalevskiy on behalf of the Authors (17 Aug 2023) Author's response Manuscript

Journal article(s) based on this preprint

25 Sep 2023

Brief communication: Identification of tundra topsoil frozen/thawed state from SMAP and GCOM-W1 radiometer measurements using the spectral gradient method

Konstantin Muzalevskiy, Zdenek Ruzicka, Alexandre Roy, Michael Loranty, and Alexander Vasiliev

The Cryosphere, 17, 4155–4164, https://doi.org/10.5194/tc-17-4155-2023,https://doi.org/10.5194/tc-17-4155-2023, 2023

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Konstantin Muzalevskiy et al.

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A new all-weather method for determining the thawed or frozen state of soils in the Arctic region based on satellite data is proposed. Testing of the method was carried out at the test sites in Canada, Finland, Russia, and U.S., which are equipped with soil-climatic weather stations. The proposed method with a high degree of reliability and better accuracy, in comparison with existing microwave satellite methods, will identify the thawed or frozen state of Arctic soils.


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