judithas

• Aspaas, Andreas Grøvan; Bievre, Grégory; Lacroix, Pascal; Langet, Nadege; Aga, Juditha & Skrede, Ingrid [Show all 9 contributors for this article] (2026). Seasonal and inter-annual evolution of the deformation of two Arctic landslides. Earth Surface Dynamics. ISSN 2196-6311. 14(5), p. 729–761. doi: 10.5194/esurf-14-729-2026. Full text in Research Archive Show summary

  Landslides in glacial and periglacial environments are increasingly affected by climate change, with sudden failures reported in high mountain regions and the Arctic. The complex mechanisms behind these events are often poorly understood due to a lack of dense in situ data. We investigate two slow-moving landslides in Arctic Norway (70° N), the Jettan and Gámanjunni landslides, located approximately 10 km apart: Jettan, a complex slide in micaschist and calcite marble situated below the permafrost boundary, and Gámanjunni, a rotational slide in micaschist situated above the permafrost boundary. Using over a decade of multi-physics observations, including geodetic, borehole, seismic, and hydrological data, we examine surface and subsurface deformation. Both landslides display similar seasonal surface velocity patterns, with peaks in spring and autumn, likely influenced by pore-water infiltration. At Jettan, twelve years of inclinometer data in boreholes reveal a transition from steady state to seasonal deformation in two shear zones. Since 2020, spring accelerations have intensified in years coinciding with deeper snowpacks and associated melt. These observations, together with statistical modeling, suggest that the shear-zones are becoming increasingly localized and sensitive to pore-water pressure. Conversely, autumn acceleration is not seen in localized shear zones but manifests as distributed volumetric deformation. Seismic velocity variations within the landslide body also exhibit seasonal patterns that correspond with geodetic velocity, interpreted as changes in landslide rigidity due to water infiltration. This integrated analysis of surface and subsurface data offers new insights into the evolving deformation of Arctic landslides, emphasizing the influence of hydrological forcings on both seasonal and long-term deformation processes.

• Aga, Juditha; Willmes, Clarissa; Sinitsyn, Anatoly; Arlov, Thor Bjørn; Boike, Julia & Westermann, Sebastian (2025). Impact of snow and building management on ground surface temperatures in permafrost environments - A case study from the historical mining town Ny-Ålesund, Svalbard. Cold Regions Science and Technology. ISSN 0165-232X. 237, p. 1–12. doi: 10.1016/j.coldregions.2025.104516. Full text in Research Archive Show summary

  Permafrost is warming due to changing climatic conditions, a trend that might threaten infrastructure and livelihood across the Arctic. Historical structures are especially vulnerable, as they were not designed to withstand these rapid environmental changes. In the high-Arctic settlement Ny-Ålesund, Svalbard, a large number of historical buildings exist, making the village a suitable case study for investigating the interplay between historical buildings and permafrost. This study analysed two years of ground surface temperature (GST) measurements and snow observations to assess the impact of snow and building management on permafrost conditions in Ny-Ålesund. The mean annual ground surface temperature (MAGST) was found between −1.9°C and 1.9°C in 2022/23, and between −3.1°C and 1.1°C in 2023/24. The results reveal that GST varied substantially within the village area and exceeded the freezing point in several locations. We identified influencing factors contributing to these differences in GST: (i) Snow redistribution by wind and snow ploughing caused large variations in GST with the highest MAGST beneath artificial snow deposits. (ii) Building type, particularly crawl space ventilation, also affected GST. Ventilated crawl spaces tended to lower the MAGST beneath the buildings, while enclosed crawl spaces increased MAGST to positive values. (iii) Building wall orientation further influenced GST, with southern exposures exhibiting higher values compared to northern exposures. Our findings highlight the importance of snow and building management on GST and permafrost stability. Understanding these small scale effects is crucial for the preservation of historical infrastructure on permafrost under changing climatic conditions.

• Kuhn, Dirk; Hermanns, Reginald Leonhard Manfred; Fuchs, Michael; Schüßler, Nick; Torizin, Jewgenij & Aga, Juditha [Show all 9 contributors for this article] (2025). Warming-induced destabilization of polar coastal rock cliffs and the role of thermokarst: A case study of Forkastningsfjellet on Svalbard. Science of the Total Environment. ISSN 0048-9697. 968. doi: 10.1016/j.scitotenv.2025.178807. Full text in Research Archive Show summary

  Deep-seated landslides pose a potential threat to coastal settlements, shipping routes, and the natural environment of the polar regions. However, the occurrence, dynamics and impact of such landslides under a warming climate are poorly understood owing to scarce observational data. Here we investigate two deep-seated rockslides on the permafrost coastline of Forkastningsfjellet, Svalbard. Along this coastline, which was dormant for at least the last 80 years, a 175,000 m3 rockslide occurred in August 2016, followed by a second rockslide of 750,000 m3 in November 2022. Based on extensive field data collection starting in 2017, which includes the acquisition and differencing of drone-based DEMs, point-based displacement measurements (dGNSS), ground surface temperature logging, and field mapping, we document accelerating surface deformation and the redirection of the drainage pathways that drive the dynamics of the unstable slope. We show that the 2022 rock slope failure was governed by rapid fluvial incision and accelerated thermokarst development along colluvium-covered, pre-existing zones of weakness, which we interpret as permafrost degradation and enhanced surface run-off resulting from climate warming. We attribute the final triggering of the rockslide to the loss of cohesion and increasing pore water pressures due to thawing ground and cleft ice within the joint system. Looking to the future, we argue for the likely emergence of a positive feedback loop between increasing water availability, due to permafrost thaw and changing precipitation trends, and rock mass deformation.

• Aga, Juditha; Piermattei, Livia; Girod, Luc; Aalstad, Kristoffer; Eiken, Trond & Kääb, Andreas [Show all 7 contributors for this article] (2024). Acceleration of coastal-retreat rates for high-Arctic rock cliffs on Brøggerhalvøya, Svalbard, over the past decade. Earth Surface Dynamics. ISSN 2196-6311. 12(5), p. 1049–1070. doi: 10.5194/esurf-12-1049-2024. Full text in Research Archive Show summary

  In many Arctic regions, marine coastlines change rapidly in our currently warming climate. In contrast, coastal rock cliffs on Svalbard are considered to be relatively stable. Long-term trends of coastal-retreat rates for rock cliffs on Svalbard remain unknown, but quantifying them could improve our understanding of coastal dynamics in the Canadian Arctic Archipelago. This study presents coastal-retreat rates for rock cliffs along several kilometres of Brøggerhalvøya, Svalbard. The analysis relies on high-resolution orthoimages from 1970, 1990, 2010, and 2021. The data are corroborated by high-precision dGNSS (differential Global Navigation Satellite System) measurements obtained along selected segments of the coastline. Our analysis reveals statistically significant acceleration in coastal-retreat rates across Brøggerhalvøya between 2010 and 2021. The northeast-facing coastline features fairly stable conditions, with retreat rates of 0.04 ± 0.06 m a−1 (1970–1990; calculated retreat rate ± the corresponding measurement uncertainty), 0.04 ± 0.04 m a−1 (1990–2010), and 0.06 ± 0.08 m a−1 (2010–2021). Along the southwest-facing coastline, higher retreat rates of 0.26 ± 0.06 m a−1 (1970–1990), 0.24 ± 0.04 m a−1 (1990–2010), and 0.30 ± 0.08 m a−1 (2010–2021) were calculated. For the most recent decade, this corresponds to an increase of 50 % for the northeast-facing coastline and an increase of 25 % for the southwest-facing coastline. Furthermore, for the northeast-facing coastline, the proportion of the coastline affected by erosion increased from 47 % (1970–1990) to 65 % (2010–2021), while it stayed consistently above 90 % for the southwest-facing coastline. The recent acceleration in retreat rates coincides with increasing storminess and retreating sea ice, factors that can enhance coastal erosion.

• Renette, Cas; Aalstad, Kristoffer; Aga, Juditha; Zweigel, Robin Benjamin; Etzelmüller, Bernd & Lilleøren, Karianne Staalesen [Show all 8 contributors for this article] (2023). Simulating the effect of subsurface drainage on the thermal regime and ground ice in blocky terrain in Norway. Earth Surface Dynamics. ISSN 2196-6311. 11(1), p. 33–50. doi: 10.5194/esurf-11-33-2023. Full text in Research Archive Show summary

  Ground temperatures in coarse, blocky deposits such as mountain blockfields and rock glaciers have long been observed to be lower in comparison with other (sub)surface material. One of the reasons for this negative temperature anomaly is the lower soil moisture content in blocky terrain, which decreases the duration of the zero curtain in autumn. Here we used the CryoGrid community model to simulate the effect of drainage on the ground thermal regime and ground ice in blocky terrain permafrost at two sites in Norway. The model set-up is based on a one-dimensional model domain and features a surface energy balance, heat conduction and advection, as well as a bucket water scheme with adjustable lateral drainage. We used three idealized subsurface stratigraphies, blocks only, blocks with sediment and sediment only, which can be either drained (i.e. with strong lateral subsurface drainage) or undrained (i.e. without drainage), resulting in six scenarios. The main difference between the three stratigraphies is their ability to retain water against drainage: while the blocks only stratigraphy can only hold small amounts of water, much more water is retained within the sediment phase of the two other stratigraphies, which critically modifies the freeze–thaw behaviour. The simulation results show markedly lower ground temperatures in the blocks only, drained scenario compared to other scenarios, with a negative thermal anomaly of up to 2.2 ∘C. For this scenario, the model can in particular simulate the time evolution of ground ice, with build-up during and after snowmelt and spring and gradual lowering of the ice table in the course of the summer season. The thermal anomaly increases with larger amounts of snowfall, showing that well-drained blocky deposits are less sensitive to insulation by snow than other soils. We simulate stable permafrost conditions at the location of a rock glacier in northern Norway with a mean annual ground surface temperature of 2.0–2.5 ∘C in the blocks only, drained simulations. Finally, transient simulations since 1951 at the rock glacier site (starting with permafrost conditions for all stratigraphies) showed a complete loss of perennial ground ice in the upper 5 m of the ground in the blocks with sediment, drained run; a 1.6 m lowering of the ground ice table in the sediment only, drained run; and only 0.1 m lowering in the blocks only, drained run. The interplay between the subsurface water–ice balance and ground freezing/thawing driven by heat conduction can at least partly explain the occurrence of permafrost in coarse blocky terrain below the elevational limit of permafrost in non-blocky sediments. It is thus important to consider the subsurface water–ice balance in blocky terrain in future efforts in permafrost distribution mapping in mountainous areas. Furthermore, an accurate prediction of the evolution of the ground ice table in a future climate can have implications for slope stability, as well as water resources in arid environments.

• Westermann, Sebastian; Ingeman-Nielsen, Thomas; Scheer, Johanna; Aalstad, Kristoffer; Aga, Juditha & Chaudhary, Nitin [Show all 24 contributors for this article] (2023). The CryoGrid community model (version 1.0) - a multi-physics toolbox for climate-driven simulations in the terrestrial cryosphere. Geoscientific Model Development. ISSN 1991-959X. 16(9), p. 2607–2647. doi: 10.5194/gmd-16-2607-2023. Full text in Research Archive Show summary

  The CryoGrid community model is a flexible toolbox for simulating the ground thermal regime and the ice–water balance for permafrost and glaciers, extending a well-established suite of permafrost models (CryoGrid 1, 2, and 3). The CryoGrid community model can accommodate a wide variety of application scenarios, which is achieved by fully modular structures through object-oriented programming. Different model components, characterized by their process representations and parameterizations, are realized as classes (i.e., objects) in CryoGrid. Standardized communication protocols between these classes ensure that they can be stacked vertically. For example, the CryoGrid community model features several classes with different complexity for the seasonal snow cover, which can be flexibly combined with a range of classes representing subsurface materials, each with their own set of process representations (e.g., soil with and without water balance, glacier ice). We present the CryoGrid architecture as well as the model physics and defining equations for the different model classes, focusing on one-dimensional model configurations which can also interact with external heat and water reservoirs. We illustrate the wide variety of simulation capabilities for a site on Svalbard, with point-scale permafrost simulations using, e.g., different soil freezing characteristics, drainage regimes, and snow representations, as well as simulations for glacier mass balance and a shallow water body. The CryoGrid community model is not intended as a static model framework but aims to provide developers with a flexible platform for efficient model development. In this study, we document both basic and advanced model functionalities to provide a baseline for the future development of novel cryosphere models.

• Aga, Juditha; Boike, Julia; Langer, Moritz; Ingeman-Nielsen, Thomas & Westermann, Sebastian (2023). Simulating ice segregation and thaw consolidation in permafrost environments with the CryoGrid community model. The Cryosphere. ISSN 1994-0416. 17(10), p. 4179–4206. doi: 10.5194/tc-17-4179-2023. Full text in Research Archive Show summary

  Abstract. The ground ice content in cold environments influences the permafrost thermal regime and the thaw trajectories in a warming climate, especially for soils containing excess ice. Despite their importance, the amount and distribution of ground ice are often unknown due to lacking field observations. Hence, modeling the thawing of ice-rich permafrost soils and associated thermokarst is challenging as ground ice content has to be prescribed in the model setup. In this study, we present a model scheme, capable of simulating segregated ice formation during a model spinup together with associated ground heave. It provides the option to add a constant sedimentation rate throughout the simulation. Besides ice segregation, it can represent thaw consolidation processes and ground subsidence under a warming climate. The computation is based on soil mechanical processes, soil hydrology by the Richards equation and soil freezing characteristics. The code is implemented in the CryoGrid community model (version 1.0), a modular land surface model for simulations of the ground thermal regime. The simulation of ice segregation and thaw consolidation with the new model scheme allows us to analyze the evolution of ground ice content in both space and time. To do so, we use climate data from two contrasting permafrost sites to run the simulations. Several influencing factors are identified, which control the formation and thaw of segregated ice. (i) Model results show that high temperature gradients in the soil as well as moist conditions support the formation of segregated ice. (ii) We find that ice segregation increases in fine-grained soils and that especially organic-rich sediments enhance the process. (iii) Applying external loads suppresses ice segregation and speeds up thaw consolidation. (iv) Sedimentation leads to a rise of the ground surface and the formation of an ice-enriched layer whose thickness increases with sedimentation time. We conclude that the new model scheme is a step forward to improve the description of ground ice distributions in permafrost models and can contribute towards the understanding of ice segregation and thaw consolidation in permafrost environments under changing climatic conditions.

• Schmidt, Juditha; Etzelmüller, Bernd; Schuler, Thomas; Magnin, Florence; Boike, Julia & Langer, Moritz [Show all 7 contributors for this article] (2021). Surface temperatures and their influence on the permafrost thermal regime in high-Arctic rock walls on Svalbard. The Cryosphere. ISSN 1994-0416. 15(5), p. 2491–2509. doi: 10.5194/tc-15-2491-2021. Full text in Research Archive Show summary

  Abstract. Permafrost degradation in steep rock walls and associated slope destabilization have been studied increasingly in recent years. While most studies focus on mountainous and sub-Arctic regions, the occurring thermo-mechanical processes also play an important role in the high Arctic. A more precise understanding is required to assess the risk of natural hazards enhanced by permafrost warming in high-Arctic rock walls. This study presents one of the first comprehensive datasets of rock surface temperature measurements of steep rock walls in the high Arctic, comparing coastal and near-coastal settings. We applied the surface energy balance model CryoGrid 3 for evaluation, including adjusted radiative forcing to account for vertical rock walls. Our measurements comprise 4 years of rock surface temperature data from summer 2016 to summer 2020. Mean annual rock surface temperatures ranged from −0.6 in a coastal rock wall in 2017/18 to −4.3 ∘C in a near-coastal rock wall in 2019/20. Our measurements and model results indicate that rock surface temperatures at coastal cliffs are up to 1.5 ∘C higher than at near-coastal rock walls when the fjord is ice-free in winter, resulting from additional energy input due to higher air temperatures at the coast and radiative warming by relatively warm seawater. An ice layer on the fjord counteracts this effect, leading to similar rock surface temperatures to those in near-coastal settings. Our results include a simulated surface energy balance with shortwave radiation as the dominant energy source during spring and summer with net average seasonal values of up to 100 W m−2 and longwave radiation being the main energy loss with net seasonal averages between 16 and 39 W m−2. While sensible heat fluxes can both warm and cool the surface, latent heat fluxes are mostly insignificant. Simulations for future climate conditions result in a warming of rock surface temperatures and a deepening of active layer thickness for both coastal and near-coastal rock walls. Our field data present a unique dataset of rock surface temperatures in steep high-Arctic rock walls, while our model can contribute towards the understanding of factors influencing coastal and near-coastal settings and the associated surface energy balance.

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• Sinitsyn, Anatoly; Bekele, Yared Worku; Vehola, Anni; Rubensdotter, Brita Lena Eleonor Fredin; Westermann, Sebastian & Aga, Juditha (2025). Presentation from WP1 Input in managing strategies. Based on input from WP3 and WP4. Full text in Research Archive
• Aga, Juditha & Westermann, Sebastian (2025). Update PCCH-WP3. Full text in Research Archive
• Aga, Juditha & Willmes, Clarissa (2024). Ground surface temperature measurements and snow observations in Ny-Ålesund, Svalbard (2022-2024). doi: 10.5281/zenodo.14380247. Full text in Research Archive
• Aga, Juditha & Westermann, Sebastian (2024). Projected permafrost changes. Full text in Research Archive
• Sinitsyn, Anatoly; Westermann, Sebastian; Arlov, Thor Bjørn; Landgren, Oskar Andreas; Meyer, Alexandra & Aga, Juditha [Show all 8 contributors for this article] (2024). Sammendrag om det PCCH-Arctic prosjektet. Full text in Research Archive
• Aga, Juditha; Westermann, Sebastian; Landgren, Oskar Andreas; Willmes, Clarissa & Sinitsyn, Anatoly (2023). Cultural heritage in a changing climate. In al., - et (Eds.), Svalbard Science Conference 2023. Book of Abstracts. SSC . ISSN 9780000000019. Full text in Research Archive
• Aga, Juditha; Westermann, Sebastian; Landgren, Oskar Andreas; Willmes, Clarissa & Sinitsyn, Anatoly (2023). Cultural heritage in a changing climate: The crucial role of snow management and the influence of warming permafrost on historical buildings in Ny-Ålesund. In al., - et (Eds.), Svalbard Science Conference 2023. Book of Abstracts. SSC . ISSN 9780000000019. p. 235–235. Full text in Research Archive
• Sinitsyn, Anatoly; Meyer, Alexandra; Aga, Juditha; Lutz, Julia & Landgren, Oskar Andreas (2023). Towards a better management of cultural heritage in changing Polar regions: Introducing the project PCCH-Arctic. In al, . et (Eds.), ASSW 2023 Science Symposium "The Arctic in the Anthropocene". Book of abstracts 17 – 24 February 2023 Vienna, Austria. Arctic Science Summit Week 2023. ISSN 9780000000019. Full text in Research Archive
• Sinitsyn, Anatoly; Aga, Juditha; Arlov, Thor Bjørn; Bekele, Yared Worku; Seljelv, Ingalill Johansen & Landgren, Oskar Andreas [Show all 13 contributors for this article] (2023). Polar Climate and Cultural Heritage: outline of the PCCH-Arctic project and first results. In al., - et (Eds.), Svalbard Science Conference 2023. Book of Abstracts. SSC . ISSN 9780000000019. p. 234–234. Full text in Research Archive
• Sinitsyn, Anatoly; Westermann, Sebastian; Arlov, Thor Bjørn; Landgren, Oskar Andreas; Meyer, A. & Lutz, J. [Show all 8 contributors for this article] (2022). PCCH-Arctic – Polar Climate and Cultural Heritage – Preservation and Restoration Management. Full text in Research Archive
• Sinitsyn, Anatoly; Bekele, Yared Worku; Vehola, Anni; Rubensdotter, Brita Lena Eleonor Fredin; Westermann, Sebastian & Aga, Juditha (2025). Input in managing strategies. Recommendations for the objects managed by the user partners in PCCH-Arctic. SINTEF Community. ISSN 9788214075274. doi: 10.5281/zenodo.17099422. Full text in Research Archive Show summary

  This report presents input for managing strategies of selected objects of technicalindustrial cultural heritage in Longyearbyen and Ny-Ålesund. In particular, the report provides results of condition survey of cableway trestles in Longyearbyen, assessment of natural hazard impacts on case study objects, recommendations for special case study objects, in addition to recommendations for monitoring and sources of data on climate projections.

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