the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 09 Mar 2026
Inversion of ground ice content using coupled multi-source electromagnetic parameters in the source region of the Yellow River on the Tibetan Plateau
Abstract. Ground ice content plays a key role in controlling permafrost stability in the source region of the Yellow River, yet its quantitative characterization is limited by strong subsurface heterogeneity and scarce direct observations. This study integrated ground-penetrating radar (GPR) and opposing coils transient electromagnetic (OCTEM) data within a joint inversion framework based on full-waveform inversion (FWI) to estimate volumetric ice content (VIC) at four high-altitude permafrost sites. The results showed strong lateral and vertical variability in VIC, with distinct VIC magnitudes and depth-dependent patterns among sites. Shallow VIC derived from radar-based dielectric properties provided physical constraints for estimating deeper VIC through a calibrated relationship between relative permittivity and apparent resistivity. Ice-rich and ice-poor zones were spatially consistent with apparent resistivity sections and forward-modeled electromagnetic responses, supporting the reliability of the integrated approach. Estimated VIC at depths from 2 to 10 m was relatively low at Huashixia, at approximately 8–15 %, but generally exceeded 20 % at Hela, Shuangchagou, and Maduo. This study demonstrated the effectiveness of a physically constrained electromagnetic strategy for quantifying VIC in alpine permafrost.
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- RC1: 'Comment on egusphere-2026-828', Vincenzo Lapenna, 10 Aug 2026
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RC2: 'Comment on egusphere-2026-828', Anonymous Referee #2, 16 Aug 2026
The article presents a newly developed approach for deriving volumetric ice content (VIC) based on coupled multi-source electromagnetic surveys. The geophysical methods are described in considerable detail, and the study includes validation of the derived results. The approach is interesting and potentially useful for permafrost characterization. However, several aspects of the manuscript would benefit from clarification or additional information:
- The manuscript contains a large number of abbreviations, which can make it difficult to follow, particularly when terms are encountered long after they are first introduced. I suggest adding a dedicated “Abbreviations” section or list to improve readability.
- The Introduction would benefit from additional discussion of existing approaches for estimating volumetric ice content from geophysical observations. In particular, I suggest adding a brief overview of previously used geophysical methods and models for VIC estimation and explaining how the approach presented in this study differs from or advances these existing approaches.
- The Study Site section is missing some information that would help readers interpret the geophysical results. What are the general characteristics of permafrost in the study region, including its approximate thickness and typical active-layer depth? Is the study area located within the continuous permafrost zone? If possible, it would also be useful to indicate the boundaries of continuous and discontinuous permafrost on the regional map. In addition, please provide information about the dominant sediments or surficial geology at the study site, as these characteristics may influence the geophysical measurements and their interpretation.
- More information is needed about how the ground-truth volumetric water content (VWC) and volumetric ice content (VIC) data were collected. How many samples or measurements were obtained? What was their spatial distribution—for example, were they collected along a grid or transect, and what was the approximate spacing between sampling locations? At what depths were the samples collected? Were measurements obtained from the active layer, frozen permafrost, or both? Please also clarify whether VWC and VIC were measured directly in the field or determined from samples analyzed in the laboratory, and briefly describe the methods used.
- Please specify how many ground-truth measurements were used for model validation. It would also be helpful to clarify whether the validation dataset was independent of the data used for model development/calibration and how the validation locations were selected.
- Figure 4 requires a legend so that the symbols, colors, and/or categories shown in the figure can be clearly interpreted.
Overall, this is an interesting study that presents a promising approach for estimating volumetric ice content from integrated geophysical observations. I believe that addressing the points above would improve the clarity and reproducibility of the study and strengthen the presentation and interpretation of the results.
Citation: https://doi.org/10.5194/egusphere-2026-828-RC2
Status: closed
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RC1: 'Comment on egusphere-2026-828', Vincenzo Lapenna, 10 Aug 2026
The topic and study area of this work are very interesting and fit the scope of the journal. There is a growing interest in the geophysical monitoring of permafrost, so papers on this topic are welcome and must be encouraged.
However, I must point out several critical issues with the manuscript. The authors claim to have used geophysical inversion to obtain the ground ice content at four sites, but the methodological approach to the claimed data inversion is unclear. They used apparent resistivity values obtained using an electromagnetic method to evaluate the relative permittivity in a purely qualitative way without any serious experimental or objective constraints. The processing of the GPR data is completely unclear.
There is no mention of the novelty of the methodological approach or of any serious validation of the results. It is impossible to evaluate the quality of the results or the advantages of the proposed approach over other methods.
Furthermore, the figure captions are not fully informative, making it difficult to evaluate the quality of the results. Equations 1 and 2 are unnecessary and scholastic.
Based on these considerations, I cannot recommend publishing this paper. I can only recommend completely reorganising the paper, reducing the claims about inversion and providing a thorough description of the results. After a complete reorganization, I suggest resubmitting the manuscript.Citation: https://doi.org/10.5194/egusphere-2026-828-RC1 -
RC2: 'Comment on egusphere-2026-828', Anonymous Referee #2, 16 Aug 2026
The article presents a newly developed approach for deriving volumetric ice content (VIC) based on coupled multi-source electromagnetic surveys. The geophysical methods are described in considerable detail, and the study includes validation of the derived results. The approach is interesting and potentially useful for permafrost characterization. However, several aspects of the manuscript would benefit from clarification or additional information:
- The manuscript contains a large number of abbreviations, which can make it difficult to follow, particularly when terms are encountered long after they are first introduced. I suggest adding a dedicated “Abbreviations” section or list to improve readability.
- The Introduction would benefit from additional discussion of existing approaches for estimating volumetric ice content from geophysical observations. In particular, I suggest adding a brief overview of previously used geophysical methods and models for VIC estimation and explaining how the approach presented in this study differs from or advances these existing approaches.
- The Study Site section is missing some information that would help readers interpret the geophysical results. What are the general characteristics of permafrost in the study region, including its approximate thickness and typical active-layer depth? Is the study area located within the continuous permafrost zone? If possible, it would also be useful to indicate the boundaries of continuous and discontinuous permafrost on the regional map. In addition, please provide information about the dominant sediments or surficial geology at the study site, as these characteristics may influence the geophysical measurements and their interpretation.
- More information is needed about how the ground-truth volumetric water content (VWC) and volumetric ice content (VIC) data were collected. How many samples or measurements were obtained? What was their spatial distribution—for example, were they collected along a grid or transect, and what was the approximate spacing between sampling locations? At what depths were the samples collected? Were measurements obtained from the active layer, frozen permafrost, or both? Please also clarify whether VWC and VIC were measured directly in the field or determined from samples analyzed in the laboratory, and briefly describe the methods used.
- Please specify how many ground-truth measurements were used for model validation. It would also be helpful to clarify whether the validation dataset was independent of the data used for model development/calibration and how the validation locations were selected.
- Figure 4 requires a legend so that the symbols, colors, and/or categories shown in the figure can be clearly interpreted.
Overall, this is an interesting study that presents a promising approach for estimating volumetric ice content from integrated geophysical observations. I believe that addressing the points above would improve the clarity and reproducibility of the study and strengthen the presentation and interpretation of the results.
Citation: https://doi.org/10.5194/egusphere-2026-828-RC2
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The topic and study area of this work are very interesting and fit the scope of the journal. There is a growing interest in the geophysical monitoring of permafrost, so papers on this topic are welcome and must be encouraged.
However, I must point out several critical issues with the manuscript. The authors claim to have used geophysical inversion to obtain the ground ice content at four sites, but the methodological approach to the claimed data inversion is unclear. They used apparent resistivity values obtained using an electromagnetic method to evaluate the relative permittivity in a purely qualitative way without any serious experimental or objective constraints. The processing of the GPR data is completely unclear.
There is no mention of the novelty of the methodological approach or of any serious validation of the results. It is impossible to evaluate the quality of the results or the advantages of the proposed approach over other methods.
Furthermore, the figure captions are not fully informative, making it difficult to evaluate the quality of the results. Equations 1 and 2 are unnecessary and scholastic.
Based on these considerations, I cannot recommend publishing this paper. I can only recommend completely reorganising the paper, reducing the claims about inversion and providing a thorough description of the results. After a complete reorganization, I suggest resubmitting the manuscript.