HIT Permafrost

The Hidden Image of Thawing Permafrost

The project aims to develop a method for determining just how extensively thaw processes have already progressed in permafrost regions. The machine learning approach to be developed will be used to analyse radar images from aircraft in order to learn more about the properties of the subsurface permafrost.

Thawing permafrost at Trail Valley Creek in Canada may bring uncertainty for the entire region: roads and buildings could lose their solid foundations if the ground subsides. Also, the thawing of permafrost everywhere in the world – be it in Canada, Siberia, or other parts of the Arctic – serves as an indicator of global warming.

“Permafrost is a phenomenon that occurs under the surface of the soil, and is therefore difficult to measure,” says Julia Boike of the Alfred Wegener Institute (AWI). Even under coverings of permanent ice, experts believe, there are vast areas in which the ground has irreversibly thawed. These areas of unfrozen ground in permafrost regions are known as talik. Exactly where these are located and how extensive they are, however, is as yet unknown.

This project proposes a method for quantifying the properties of subsurface permafrost. This will reveal how rapidly ground thaw is progressing. The area of investigation is at Trail Valley Creek, located at the forest-tundra boundary in the North West Canadian permafrost zone. The researchers are developing an approach that will combine a physical permafrost model with data newly obtained from aerial images as well as with interferometry, tomography, and polarimetry information obtained from radar data. “We have many datasets from past measurement campaigns, which we want to combine and interpret together in order to learn more about the conditions of the ground,” says Irena Hajnsek of the German Aerospace Center (DLR).


Hammar, J., Grünberg, I., Kokelj, S. V., van der Sluijs, J., & Boike, J. (2023). Snow accumulation, albedo and melt patterns following road construction on permafrost, Inuvik–Tuktoyaktuk Highway, Canada. The Cryosphere, 17(12), 5357–5372. https://doi.org/10.5194/tc-17-5357-2023
Saporta, P., Alonso-Gonzalez, A., & Hajnsek, I. (2023, February). Assessing Polarimetric SAR Interferometry coherence region parameters over a permafrost landscape. POLinSAR Online Abstracts. ESA POLinSAR Workshop, Toulouse, France. https://elib.dlr.de/194470/
Saporta, P., Alonso-González, A., & Hajnsek, I. (2023). Investigating signal penetration depth in Synthetic Aperture Radar imagery over lowland permafrost. In J. M. Fernández-Fernández, J. Bonsoms, J. García-Oteyza, & M. Oliva (Eds.), Book of abstracts (p. 246). https://doi.org/10.52381/EUCOP6.abstracts.1
Hammar, J., Grünberg, I., Hendricks, S., Jutila, A., Helm, V., & Boike, J. (2023). Snow covered digital elevation model and snow depth product (2019), Trail Valley Creek, NWT, Canada. PANGAEA. https://doi.org/10.1594/PANGAEA.962552
Nill, L., Grünberg, I., Ullmann, T., Gessner, M., Boike, J., & Hostert, P. (2022). Arctic shrub expansion revealed by Landsat-derived multitemporal vegetation cover fractions in the Western Canadian Arctic. Remote Sensing of Environment, 281, 113228. https://doi.org/10.1016/j.rse.2022.113228
Saporta, P., Hajnsek, I., & Alonso-Gonzalez, A. (2022). A temporal assessment of fully polarimetric multifrequency SAR observations over the Canadian permafrost. Proceedings of the European Conference on Synthetic Aperture Radar, EUSAR. European Conference on Synthetic Aperture Radar, EUSAR, Leipzig, Germany. https://elib.dlr.de/186412/
Lange, S., Grünberg, I., Anders, K., Hartmann, J., Helm, V., & Boike, J. (2021). Airborne Laser Scanning (ALS) Point Clouds of Trail Valley Creek, NWT, Canada (2018). https://doi.org/10.1594/PANGAEA.934387
Gonstalla, E., Grünberg, I., & Boike, J. (2021). Das Eisbuch - Alles, was man wissen muss, in 50 Grafiken. oekom Verlag.

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