The mountain cryosphere responds very sensitively to global climate change because of local processes and positive feedbacks, with far-reaching hydrological, ecological and socio-economic consequences at different spatial scales. To uncover rapid changes, assess potential impacts and develop effective adaptation strategies, comprehensive monitoring of the state and evolution of the mountain cryosphere is essential. In recent years, unoccupied aerial vehicles (UAVs) equipped with cameras or geophysical and meteorological instruments have been increasingly deployed for detailed mapping and monitoring of the mountain cryosphere. UAVs facilitate a wide range of geoscientific applications and are particularly useful for surveying areas in alpine terrain that are difficult to access. They also have great potential for the spatial study of small-scale and dynamic processes. Using high-resolution digital elevation models or dense point clouds from (repeated) UAV surveys has become a widespread method for mapping snow depth changes and quantifying glacier volume loss. The ongoing miniaturisation of electronic sensors and the specific development of multispectral and thermal infrared cameras, GPR and LiDAR systems and other geophysical instruments for UAV-based surveys have opened up new opportunities for cryospheric research in complex terrain. Recent advances include the measurement of glacier thickness and snow depth using UAV-borne GPR, the mapping of supraglacial debris thickness and permafrost distribution using UAV-based thermal infrared thermography, the mapping of snow and ice albedo using UAV-based multispectral imaging, and the investigation of the atmospheric boundary layer over ice and snow using UAVs. Here I briefly discuss the potential and limitations of recent advances in UAV technology for cryospheric research and outline future prospects for the detailed monitoring of mountain glaciers, permafrost and snow cover.

How to cite: Groos, A. R.: UAV-based monitoring of the mountain cryosphere: Recent advances and future prospects, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13712, https://doi.org/10.5194/egusphere-egu25-13712, 2025.

The CRYO-RI project establishes a comprehensive research infrastructure to investigate and monitor the rapid transformations in snow, ice, and frozen ground in Northern Finland. Recognizing the need to reassess historical projections and governance frameworks related to cryospheric systems, the project focuses on documenting these changes with high-quality, dynamic monitoring systems. CRYO-RI addresses this pressing challenge through a regionally focused, interdisciplinary snow and ice research infrastructure cluster. The consortium comprises the University of Oulu, the Finnish Meteorological Institute (FMI), the Finnish Environment Institute (SYKE), and the Geological Survey of Finland (GTK).

This presentation highlights the advancements in snow and ice monitoring infrastructure achieved within the CRYO-RI project. Key developments include: (i) innovative temperature-based approaches for monitoring snow, permafrost, and river ice conditions using low-cost IoT sensors, distributed temperature sensing with optical cables, and Simba equipment, (ii) updated snow field monitoring stations at the Oulanka and Sodankylä Research Stations, (iii) in-situ stable water isotope analysis of seasonal snowpacks, (iv) a river ice monitoring program, (v) GNSS-R-based snow and ice monitoring, (vi) advanced soil laboratory equipment for assessing frozen soil properties, and  (vii) UAV-based measurements using LiDAR, ground penetrating radar (GPR), and synthetic aperture radar (InSAR) sensors.

The collective efforts of the CRYO-RI consortium aim to generate novel insights, innovative measurement methodologies, and cutting-edge research at the intersection of cross-disciplinary science and cryosphere-related resource management. Additionally, the CRYO-RI platform provides open-access data and measurement infrastructure, inviting collaboration with partners from academic, public, and private sectors

How to cite: Ala-aho, P., Marttila, H., Torabi Haghighi, A., Tuomela, A., Paavola, R., Liedes, T., Sutinen, V., Anttila, K., Okkonen, J., and Kontu, A.: CRYO-RI: snow and ice monitoring and research infrastructure for Northern Finland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15704, https://doi.org/10.5194/egusphere-egu25-15704, 2025.

The amount of water stored in mountain snowpack as Snow Water Equivalent (SWE) is notably difficult to measure due to the complexity of the snowpack and the remoteness of the areas of interest. Well-established methods include in-situ coring campaigns performed by specialized personnel, estimations by computational models usually relying on meteorological observations, and remote sensing by satellites. Each method has its own limitations, leaving a gap in temporal and spatial resolution that highlights the importance of deploying proximal sensors providing continuous SWE measurements in remote areas.

Recently, probes based on the detection of cosmic rays have emerged as a suitable candidate, with the development of devices based on either the absorption of neutrons or muons by the snowpack. The detector manufactured by Finapp is characterized by the patented feature of being able to contextually detect and discriminate both neutrons and muons with the same device.

The setup for SWE measurements is composed by a Finapp probe on the ground and a reference detector on a mast, out of the snowpack, to monitor the incoming cosmic rays flux. A network of 25 such systems has been deployed on the Italian mountains of the Veneto region, spanning elevations between 1400 and 2600 m asl, integrating them to pre-existent meteo-nivological stations managed by the Regional Environmental Protection Agency of Veneto (ARPAV).

SWE can be calculated basing on the drop of either neutron counts or muons counts by the ground detector. In this presentation we will compare the two methods, with a special attention to their notably different footprint, and the advantages of their simultaneous availability will be highlighted. The SWE trends will be also compared to field campaigns, historical trends and computational models.

How to cite: Gazzola, E., Valt, M., Gianessi, S., Biasuzzi, B., and Stevanato, L.: Cosmic rays detector for the measurement of snowpack by both neutrons and muons absorption, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5893, https://doi.org/10.5194/egusphere-egu25-5893, 2025.

Monitoring snow water resources is crucial to understand the dynamics of snow-fed mountain rivers. Still, in harsh and remote environments like mountain regions using conventional measurement techniques remains particularly challenging. Cosmic-Ray Neutron Sensing (CRNS) constitutes an emerging method for autonomous and non-invasive monitoring of soil moisture and snow dynamics at intermediate spatial scales of several hectares. The method is therefore promising for monitoring snow water equivalent (SWE) in high alpine locations.

The analysis includes two sites at the Zugspitze Massif, differing in elevation and surrounding topographical features. Both sensors have been installed inside existing buildings with steep roofs to avoid snow accumulation, rather than establishing new infrastructure in complex terrain. The CRNS at the Environmental Research Station Schneefernerhaus (UFS, 2656 m a.s.l.) was installed in November 2015 in the Kugelalm located on one of the terraces. A second CRNS was installed in October 2023 in the building of “Zugspitze Geodynamic Observatory Germany” (ZUGOG) operated by the German Research Centre for Geosciences (GFZ) at the summit (2962 m a.s.l.). The CRNS signal is compared against spatially distributed reference SWE based on manual measurements, terrestrial lidar and airborne photogrammetry. Furthermore, Monte Carlo based neutron simulations using the URANOS model and a dedicated modular scenario tool (YULIA) are performed to characterize the local dynamics at the measurement sites.

First results prove that CRNS is suitable for monitoring SWE dynamics even at high alpine locations like the Zugspitze Massif. At UFS the neutron counts reveal both extremely dry years, like 2022, but also very snow-rich years, like 2019 and 2024, which were among the wettest since 2015. The high altitude, the shape of the steep topography and the rocky underground with limited soil cover reduce the statistical error and increase the seasonal dynamics in the neutron flux, facilitating CRNS based SWE monitoring. Another noteworthy aspect is, that due to the large measurement footprint of several hectares, CRNS can even be used when installed within existing buildings, thus reducing costs and limiting the environmental impact of the installation.

How to cite: Schattan, P., Krebs, N., Fersch, B., Schrön, M., Facchinetti, R., Bögl, E., Rempfer, C., Knieß, J., Wetzel, K.-F., Voigt, C., Achmüller, K., Rehm, T., Schuzl, K., and Koch, F.: Non-invasive monitoring of high-alpine snow dynamics with Cosmic-Ray neutron sensing – a case study at two locations at the Zugspitze Massif , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16989, https://doi.org/10.5194/egusphere-egu25-16989, 2025.

The development of a unified model for wet snow permittivity has remained a persistent challenge in remote sensing applications. While research conducted in the 1980s and 1990s yielded permittivity models for dry and wet snow and facilitated the development of in-situ snow probes, the application of these models in practical contexts, particularly across a broad frequency spectrum, remains an area requiring further investigation. The absence of a universally accepted model for wet snow impedes accurate retrievals of essential snow properties, including density, snow height, and liquid water content (LWC), from ground-based, drone-based, and satellite radar observations. This result in inconsistencies among LWC measurements from the different systems and retrieval methods.

The primary impediment to progress in this area is the limited availability of comprehensive reference datasets encompassing simultaneous measurements of permittivity, LWC, density, and a diverse range of snow conditions. The traditional method for LWC determination, employing freezing calorimetry, offers high accuracy under controlled conditions and with skilled operators but is characterized by a time-intensive measurement process, thereby limiting the feasibility of extensive data acquisition.

This study undertakes a re-evaluation of existing field campaign data concerning wet snow permittivity at a wide range of frequencies, considering the diverse acquisition methodologies employed and their associated limitations. By critically appraising the underlying assumptions and limitations of existing permittivity models, we seek to reconcile observed discrepancies. The ultimate objective of this research is to formulate recommendations for future field campaigns, emphasizing enhanced data quality and the resolution of existing knowledge gaps that currently limit the development of robust wet snow permittivity models across a broad frequency range spanning from the MHz to tens of GHz.

Through systematic analysis and the identification of critical knowledge gaps, this investigation will contribute to the advancement of a unified understanding of wet snow permittivity, with the potential to significantly enhance the accuracy of snow property retrievals derived from remote sensing observations.

How to cite: Marin, C.: Towards a Unified Model for Wet Snow Permittivity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16124, https://doi.org/10.5194/egusphere-egu25-16124, 2025.

Seasonal storage of liquid and frozen water in high-mountain catchments will play an increasingly important role as a hydrological buffer in rapidly deglaciating mountains, sustaining streamflow during late-summer dry phases after completion of the snowmelt. Depending on the local topo-climatic conditions, these catchments are (partly) underlain by permafrost. However, below-ground water/ice storage processes, their dynamics, and water pathways are currently poorly characterized. This holds particularly in high-mountain catchments where field data with sufficient resolution to capture the spatial variability are sparse. Among geophysical techniques, time-lapse gravimetry stands out as a method that is directly sensitive to the target quantity, mass (density) distribution changes, at an appropriate spatial scale. Time-lapse gravimetric surveys have successfully quantified groundwater storage changes in high-mountain catchments (Halloran, 2025), but have never been deployed on mountain permafrost, notably rock glaciers.
33 years after pioneering gravimetric investigation on Murtèl rock glacier (Vonder Mühll & Klingelé, 1994), we return to the site with a state-of-the-art relative spring gravimeter (Scintrex CG-6 Autograv) able to resolve water/ice storage changes at the few μGal range (corresponding to <10 cm water equivalent). First, we present results from repeat gravimetric surveys, complemented by drone-based photogrammetry, that we carried out in early and late Summer 2024. We observed significant, spatially variable gravity changes attributable to the seasonal ice loss in the coarse blocky active layer. Second, we compare our data with the 1991 measurements (Vonder Mühll & Klingélé, 1994). Finally, we discuss the strengths and limitations of time-lapse gravimetry in complex mountain permafrost terrain, including challenges related to the decomposition of the temporal gravity signal to different water and rock mass distribution changes.

References
Vonder Mühll, D. S., and Klingelé, E. E.: Gravimetrical investigation of ice-rich permafrost within the rock glacier Murtèl-Corvatsch (upper Engadin, Swiss Alps). Permafrost and Periglacial Processes, 5(1), 13–24. doi:10.1002/ppp.3430050103, 1994.
Halloran, L.J.S., Mohammadi, N., Amschwand, D., Carron, A., Gutierrez, F., Baia Sampaio, J., and Arnoux M.: Hydro-gravimetry as a monitoring solution for water and ice storage changes in dynamic alpine environments, EGU General Assembly 2025, Vienna, Austria, 27 April–2 May 2025, EGU25-3101, 2025.

How to cite: Amschwand, D., Halloran, L., Vonder Mühll, D., Hoelzle, M., and Beutel, J.: Testing time-lapse gravimetry on Murtèl rock glacier (Swiss Alps) to quantify subsurface water/ice storage changes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6793, https://doi.org/10.5194/egusphere-egu25-6793, 2025.

Degradation of mountain permafrost due to global warming reduces the stability of steep rock slopes, increasing the hazard potential for humans and infrastructure. However, detection and continuous monitoring of permafrost environments remains challenging due to the harsh conditions typically encountered in high Alpine terrain. In this study, we present results from passive seismic monitoring conducted at Mt. Zugspitze in the German/Austrian Alps.

Between 2021 and 2023, we collected continuous passive seismic data from three small seismic arrays installed along the permafrost-affected ridge to the west of the summit. This dataset is complemented by campaign-wise distributed acoustic sensing (DAS) in the tunnel systems beneath the ridge, as well as rock temperature logging and cleft water flow measurements at multiple locations near our seismic deployments.

Coda-wave interferometry reveals seasonal seismic velocity changes for most station pairs. Regarding rock temperature, pairs including stations located on the warmer south-facing slopes are primarily influenced by seasonal freezing only, whereas station pairs located on the colder north-facing slopes also indicate active-layer deepening and thus the presence of permafrost. Additionally, slant-stack analysis of DAS recordings from the northern part of the ridge also provides evidence for active-layer development during summer and fall, offering in-situ seismic observations of permafrost dynamics. Besides rock temperatures, some station pairs show a strong correlation with water flow through rock fractures, which may influence permafrost distribution.

Compared to other methods, seismology is less laborious and costly, non-invasive and allows continuous monitoring. Here, we demonstrate that it can effectively monitor freeze-thaw processes and locate permafrost. Furthermore, the results from our northern ridge deployments show evidence for extensive active-layer thaw and refreeze, indicating that permafrost may be more wide-spread than previously suggested by other studies.

How to cite: Lindner, F., Smolinski, K., Scandroglio, R., Fichtner, A., and Wassermann, J.: Permafrost Distribution and Percolating Water at Mt. Zugspitze: Insights from Seismology including DAS, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16424, https://doi.org/10.5194/egusphere-egu25-16424, 2025.

Climate change significantly impacts high-mountains worldwide, accelerating the degradation of the cryosphere. Over the last decade, numerous rockfall events involving permafrost-affected rockwalls have been recorded, especially in the European Alps. The frequency of these events is expected to increase over time due to the degradation of mountain permafrost. This study investigates permafrost dynamics at the Aiguille du Midi (3840 m a.s.l.) in the French Alps using Electrical Resistivity Tomography (ERT) monitoring over four years. A total of three profiles each 155 m in length, were deployed downwards from the summit in three directions: north-west, south and east. A system for permanent monitoring and remote data acquisition was implemented. A time-lapse inversion technique was employed for data interpretation. Laboratory measurements of electrical resistivity were conducted on granite samples in both unfrozen and frozen conditions to evaluate the temperature-dependency of resistivity. Furthermore, temperature monitoring in three boreholes provides localized information about permafrost dynamic across the site. Our ERT results demonstrate that the temperature-dependence of resistivity in field conditions is less pronounced than in controlled laboratory settings, influenced by the complexity of the site (3D effect, human-made infrastructure, rock heterogeneity (at different scales from fractures to pores) and variable ice content. In field, the freezing temperature fluctuated between -0.5 °C and -2.5 °C. Importantly, we observed that the active layer's thickness varied significantly from one face to another, with implications for the thermal regime and potential geohazards in this mountainous environment. These results are correlated with thermal information measured in boreholes. Notably, our assessments of the hydrogeological system revealed instances of water flux, although the exact pathways of infiltration and drainage remain ambiguous. This research highlights the efficacy of ERT as a low-cost, non-invasive tool for monitoring permafrost dynamics in alpine environments and highlights the need for further methodological refinement to enhance data reliability. These findings contribute to understanding potential geohazards associated with permafrost degradation and emphasize the importance of continuous monitoring in the context of ongoing climate change.

How to cite: Abdulsamad, F., Magnin, F., Revil, A., Malet, E., Richard, J., Duvillard, P.-A., and Ravanel, L.: Characterizing rockwall permafrost dynamics at Aiguille Du Midi (French Alps) through electrical resistivity tomography monitoring , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11283, https://doi.org/10.5194/egusphere-egu25-11283, 2025.

Permafrost is warming globally as shown in many recent studies based on borehole temperature monitoring. However, data on changes in ground ice and water content in permafrost areas are scarce, which are both expected to change strongly close to the melting point when latent heat effects upon melting mask further temperature increase until all ice has melted. This is the reason why permafrost borehole temperature monitoring is in many cases complemented by geophysical surveying, such as Electrical Resistivity Tomography (ERT), due to the strong dependence of electrical resistivity on liquid water content. ERT has been successfully applied to e.g. spatially map the active layer depth, quantify ice and water content and detect and delineate massive ice bodies within the permafrost since many years. In several cases survey lines were repeated or monitored over short time-periods to identify freeze-thaw processes or identify permafrost changes over longer time periods. However, only very rarely electrical resistivity is monitored operationally by an automated station.

In recent years, automated ERT (A-ERT) systems have been specifically developed to be deployed in harsh and remote terrain, and several systems have been installed in permafrost environments within different research projects. In this study, we collect and compare first results from several of these A-ERT stations regarding data quality over a full year monitoring period, specifics of current injection and contact resistances, energy consumption and resistivity evolution over freeze and thaw cycles. The continuously monitored permafrost resistivity data are compared for several A-ERT stations in polar and mountain regions, including the Antarctic Peninsula Region, Yukon and the Northwest Territories, Svalbard, Kyrgyzstan, Greenland and the European Alps. Finally, we will present processing approaches to relate the obtained resistivity changes to changes in water content and compare them to in-situ measured temperature and soil moisture data.

How to cite: Hauck, C. and the A-ERT comparison team: Comparison of Automated ERT stations (A-ERT) for continuous monitoring electrical resistivity in polar and mountain permafrost regions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15700, https://doi.org/10.5194/egusphere-egu25-15700, 2025.

Permafrost is an import carbon sink on earth and its thawing due to global warming is considered one of the most critical tipping points in climate change. Among permafrost landforms, palsas – frost-heaved mounds with ice-rich cores - are particularly sensitive to global warming. Palsas form under conditions of alternating freezing and thawing, leading to the accumulation of ice lenses that elevate the ground surface. As global temperatures rise, palsas are increasingly subject to degradation, which results in subsidence and the release of stored greenhouse gases, profoundly affecting local and global ecosystems.

This study focuses on a palsa located in a peat mire at Aidejavri/Norway, aiming to characterise it using geophysical methods. High-Frequency Induced Polarization (HFIP) was employed to quantify ice content across the palsa. HFIP is an innovative method that measures the frequency-dependent electrical conductivity in the frequency-range between 100 Hz and 100 kHz. In that range, the electrical permittivity of water ice exhibits a sharp decrease, making HFIP suitable for ice-content estimation. The HFIP data were inverted in 1D to isolate the polarization response of the subsurface from induction. A two-component dielectric mixture model was used to invert the data in 2D, providing detailed spatial insights into ice distribution. The results indicate high ice contents underneath the palsa, togehter with clear signs of degradation by decreasing ice contents at the edges where ponds are visible at the surface.

To supplement these findings, electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) were applied. ERT revealed the lateral extent and resistivity contrasts of the permafrost, while GPR delineated the upper boundary of the frozen layer. Together, these methods provided a comprehensive view of the palsa’s internal structure.

This study shows that HFIP, paired with effective pre-processing and additional methods, serves as a dependable approach for examining ice-rich permafrost. The results can be used to characterize the current state of the palsa and provide data on ice content and spatial variability. The data constitute the beginning of repetitive measurements, that aim to capture temporal changes in the palsa’s internal structure and ice content. These repeated observations will help track the dynamics of permafrost degradation over time, offering insights into how rapidly such landforms respond to climatic variations.

How to cite: Schulz, R., Burger, I., Pischke, A., Westermann, S., and Hördt, A.: Ice content estimation in a Palsa at Aidejavri (Norway) using High-Frequency Induced Polarization (HFIP), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19502, https://doi.org/10.5194/egusphere-egu25-19502, 2025.

Freeze-thaw cycles and desiccation significantly influence soil surface cracking and shrinkage, reshaping pore structures and altering hydraulic properties. Despite their importance, studies using geophysical methods to evaluate how soil crack patterns and shrinkage respond to climate change remain limited. In this study, we utilized induced polarization (IP), a sensitive and non-intrusive geophysical technique, to investigate the relationship between soil surface crack patterns and complex conductivity during freeze-thaw-desiccation and desiccation-only processes. Laboratory experiments revealed that the desiccation-only sample exhibited a distinct surface texture and different types of crack intersections compared to the freeze-thaw-desiccation sample. While Y-junction-dominated crack patterns form on the sample surface during the freeze-thaw-desiccation process, the desiccation-only sample predominantly displayed more T-junctions at the crack intersections. SIP measurements revealed a sharp decline in both in-phase and quadrature conductivities below the freezing/thawing point, with high-frequency ice polarization signals emerging. During desiccation, these components exhibited an exponential decline with a consistent decay time (τ = 358 mins). Furthermore, a clear linear relationship was observed between both conductivities and surface crack ratio, as well as gravimetric water content. These findings highlight the potential of IP for monitoring crack propagation and subsurface water dynamics in clayey soils, offering a promising tool for field applications like time-lapse tomography on clayey slopes to assess water transport and structural stability.

How to cite: Luo, H., Jost, A., Thiesson, J., Mendieta, A., Léger, E., and Jougnot, D.: Effect of surface cracking propagation on induced polarization of clay under freeze-thaw cycling and desiccation processes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6801, https://doi.org/10.5194/egusphere-egu25-6801, 2025.

On 21 June 2024, the mountain settlement of La Bérarde (French Alps) was severely damaged by a flood and debris flow. Preliminary investigations conducted by the local French authorities indicate that flooding was caused by a compound event combining (i) exceptional precipitation amounts, (ii) high snowmelt rates, and (iii) a supraglacial lake outburst flood from the nearby Glacier de la Bonne Pierre. Water balance consideration, however, indicated that additional water might have come from a subsurface reservoir, possibly located within Glacier de la Bonne Pierre. To better asses this possibility, we surveyed the glacier with a dedicated Ground Penetrating Radar (GPR) campaign in November 2024. The survey used the Airborne Ice Radar of ETH Zürich (AIRETH), a dual-polarization, helicopter-borne GPR system that has been successfully applied in previous glaciological studies.

The resulting 20 km of high-quality GPR data allowed detailed imaging of the glacier’s internal structure and bedrock. We focus on the possibility for large water accumulation within the glacier, or at the ice-bedrock interface, that could have been the origin reservoir contributing to the total flood volume. Along the glacier tongue, we detected a widely distributed, high scattering zone, indicative of temperate ice containing small water inclusions. Additional evidence of a subglacial drainage network was observed, supported by both peculiar GPR features and the presence of a river outcrop at the glacier tongue, as well as possible cavities within the ice. We applied the VAW-ETHZ package WhereTheWaterFlows.jl, which determine subglacial water flow paths, to further investigate the subglacial drainage of the glacier and validate the GPR interpretation. The outcomes of this study demonstrate the value of combining advanced geophysical techniques with modelling approaches to deepen the understanding of glacier-related hazards.

How to cite: Santin, I., Ogier, C., Moser, R., Horgan, H. J., Blanc, A., and Farinotti, D.: Helicopter-borne GPR provides insights on the 2024 La Bérarde flood , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8018, https://doi.org/10.5194/egusphere-egu25-8018, 2025.

Ice streams are important export routes for ice from the interior of ice sheets to the ocean and a key component for projecting future sea level rise under continued climate heating. Over the last years, evidence emerged that the distribution of ice crystals in and near ice streams is highly anisotropic and strongly influences the viscosity of the ice. To map this crystal orientation fabric (COF) in space, radio-echo sounding has been proven as the most effective way. Several methods to deduce COF were applied to co-polarized airborne and ground-based radar data (i.e. all antennas have the same polarization direction) and tied to ice cores, with extensive coverage available around the EastGRIP ice core to analyse the COF within the Northeast Greenland Ice Stream (NEGIS). We extended this application to a new setup of cross-polarimetric surveys with AWI's ultrawideband airborne radar system and performed several surveys over NEGIS in 2022. 
Our presentation focuses on the results of this survey obtained from established methods to obtain the COF and compares them to ground-based results, such as from phase-sensitive radio-echo sounding (pRES) and a ground-based polarimetric radar system. We discuss the advantages of operating airborne radar systems in a cross-polarized mode in contrast to only co-polarized configurations to provide insights into fabric distribution on larger spatial scales as well as the disadvantages from a lower signal-to-noise ratio for imaging the bed as well as sounding internal layers.

How to cite: Eisen, O., Jansen, D., Franke, S., Helm, V., Zeising, O., Carter, C., Gerber, T., Nymand, N., Dahl-Jensen, D., Paden, J., and Steinhage, D.: Airborne radar polarimetry over the Northeast Greenland Ice Stream, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1197, https://doi.org/10.5194/egusphere-egu25-1197, 2025.

The estimation of surface flow velocities using satellite imagery, photogrammetry, or GPS data is now a standard practice in glaciology. In contrast, assessing internal ice deformation remains a significant challenge, often relying upon sparse measurements and theoretical models constrained by limited data. This study explores the potential of repeat, common-offset, ground-penetrating radar (GPR) reflection surveys as a tool to address this challenge. While GPR reflection data are traditionally utilized to determine glacier bed geometry, they also reveal key information about internal glacier structures, including the distribution of air pockets, debris, and water channels. Over time, these structures deform in response to glacier dynamics, suggesting that time-lapse GPR measurements could offer insights into internal flow velocities. In this regard, we propose a localized cross-correlation (LCC) approach, inspired by feature-tracking methods, as a starting point for a non-linear inversion of the deformation field. We test our methodology on synthetic GPR profile data, where electromagnetic wave propagation is modeled in a simplified flowing glacier containing randomly distributed scatterers, as well as on repeat GPR profiles acquired on the Findelen Glacier, Switzerland. In both cases, the GPR measurements are considered along the direction of glacier flow, and the corresponding data are diffraction enhanced and migrated prior to analysis. Our findings demonstrate that the proposed approach successfully retrieves the two-dimensional along-flow velocity field, highlighting its potential for field applications and future extension to three-dimensions.

How to cite: Morin, A., Racz, G. C., Ruols, B., Klahold, J., Francey, M., and Irving, J.: Time-lapse GPR to quantify internal glacier deformation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13020, https://doi.org/10.5194/egusphere-egu25-13020, 2025.

Basal conditions that facilitate fast ice flow are still poorly understood and their parameterization in ice flow models results in high uncertainties in ice flow and consequent sea-level rise projections. One approach to understanding basal conditions is through investigating the basal landscape of ice streams and glaciers, which has been shaped by ice flow over the underlying substrate.

In this study, we map the subglacial landscape and identify basal conditions of Rutford Ice Stream (West Antarctica) using different visualisation techniques on high-resolution 3D radar data. Our novel approach reveals bedforms of < 300 m in length, surrounded by bedforms of > 10 km in length. We assume these variations in bedform dimension to reflect spatial variation in sediment discharge. We find no correlation to glaciological factors, but our radar data reveal a correlation between variation in bedform dimension to bed composition.

We thus developed a simple model relating sediment discharge (and hence, deformation) to inferred basal condition and measurements of basal effective pressure. The model implies that effective pressure and sediment properties (low-porosity material vs soft sediment) at the ice-bed interface are first-order controls on sediment discharge and thus bedform dimensions. This work highlights the small-scale spatial variability of basal conditions and its implications for basal slip.

Assuming glaciological factors to be constant this new approach, allows spatial variation in basal conditions and effective pressure to be identified from spatial variation in bedform dimensions, observed from high-resolution radar data. This will further allow the flow mechanism to be separated into basal slip and basal deformation and a better incorporation of their variation into numerical ice flow models.

How to cite: Schlegel, R., Zoet, L. K., Booth, A. D., Smith, A. M., Clark, R. A., and Brisbourne, A. M.: Identification of spatial variations in subglacial sediment discharge and basal slip from ground penetrating radar , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10927, https://doi.org/10.5194/egusphere-egu25-10927, 2025.

A hydrologically-active subglacial lake system has been identified near the south lateral margin of Isunnguata Sermia, West Greenland. Differencing time-stamped ArcticDEM strips has revealed multiple anomalies in ice-surface elevation change. A large hydrological drainage event from Isunnguata Sermia in 2015 slowed ice flow for ~1 month and flooded the foreland, depositing up to 8 meters of sediment. Although the proglacial flooding provided evidence that the ice-surface elevation anomalies were likely caused by subglacial water bodies, satellite altimetry cannot provide direct insights into their thickness, structure and properties. Therefore, field-based geophysical measurements, including ground-based radar and active source seismics, were collected during summer 2023 and autumn 2024 to characterise the subglacial hydrological system. 

Radar data were collected in October 2024 using a 10 MHz Blue Systems Integration ice-penetrating radar (IPR) to determine ice thickness and constrain a subglacial hydrological model. 26 km of radar data were collected over two of the ice-surface elevation anomalies. The radar data cross existing airborne IPR transects and point measurements from a phase-sensitive radar (pRES). Active source seismic surveys were performed at three locations over the largest ice-surface elevation anomaly: 1) anomaly centre, 2) anomaly southern edge, and 3) between the anomaly centre and southern edge, where bright basal reflections had been identified from radar observations. Seismic data were acquired with a hammer and plate source and 48 100 Hz vertical component geophones in a 94 m-long spread at a geophone spacing of 2 m. 

Our radar results show that the ice-surface elevation anomalies overlie complex subglacial topography on the southern sidewall of the large over-deepened trough beneath the Isunnguata Sermia trunk. Across the largest surface anomaly, ice thickness varies between 380 m to 600 m. The seismic data shows a negative polarity at the ice-bed interface, coincident with a subglacial topographic low. This indicates an acoustically soft basal material, which could represent water or water-saturated sediment. Scattering and diffraction hyperbola in the radar data arise from a complex englacial structure, which have implications for attenuation of radio and sound energy. 

These observations provide new insights into the glaciology and hydrology of an important West Greenlandic outlet glacier and highlight the complexities associated with active glacier hydrological systems and their geophysical characterisation.

How to cite: Hawkins, J., Killingbeck, S., Peacey, M., Doyle, S., Craw, L., Thorpe, S., Veness, R., Sole, A., Livingstone, S., Ross, N., Booth, A., Bagshaw, E., Prior-Jones, M., Buzzard, S., Edwards, L., and Storrar, R. and the SLIDE team: Radar and seismic investigations of an active glacier hydrological system in West Greenland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10878, https://doi.org/10.5194/egusphere-egu25-10878, 2025.

Subglacial topography and the character of a glacier’s basal material have a controlling effect on ice flow and are therefore important to parameterise in ice sheet models. Seismic surveys provide a means to characterise basal materials through the estimation of the elastic parameters of the bed (for example, acoustic impedance and Poisson’s ratio). The subglacial topography of Thwaites glacier is oriented across flow, with a series of subglacial ridges running East to West across the glacier. The bed character in the vicinity of a subglacial ridge ~60km upstream of the grounding zone, named GHOST ridge, is of particular concern, as this ridge may be a future pinning point for the grounding zone as Thwaites retreats. We present measurements of basal conditions from an active seismic dataset acquired immediately upstream of GHOST Ridge. During the 2023-24 season a 14.4 km seismic line was shot with hot water drilled Pentolite sources. We observe varied bed topography within the 14km section, with areas of smooth bed topography interspersed with rougher areas, and crag-and-tail like features present. Bed reflectivities are consistent with a widespread subglacial dilatant till layer, with stiffer till on the stoss sides of basal topographic features, and the softest till on the lee sides of these features. We will also discuss preliminary results from amplitude-versus-offset analysis, which gives further constraint of basal elastic properties.

How to cite: Agnew, R., Brisbourne, A., Anandakrishnan, S., Muto, A., Borthwick, L., Willet, A., and Melton, S. and the ITGC GHOST Team: Seismic reflection surveys at GHOST Ridge, Thwaites Glacier, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12160, https://doi.org/10.5194/egusphere-egu25-12160, 2025.

How to cite: Magyar, J., Reading, A., Turner, R., Cook, S., Winberry, P., Stål, T., McCormack, F., Kelly, I., Galton-Fenzi, B., Rosevear, M., Hudson, T., and Roberts, J.: Seismic monitoring of grounding line processes at Totten Glacier, East Antarctica, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8650, https://doi.org/10.5194/egusphere-egu25-8650, 2025.

Radio-echo sounding (RES) is a widely used tool in glaciology, providing insight into englacial and subglacial environments. Conventional high-spatial resolution RES surveys typically employ zero- or small-offset configurations with a single transmitter-receiver pair. Such surveys often prioritize spatial coverage over monitoring temporal changes in englacial and subglacial conditions. Stationary radar arrays aimed at providing time series data have been previously deployed in glaciated regions to provide estimates of basal melt rates, infer vertical strain within ice sheets, and image englacial layers in 3D. However, these stationary arrays are unable to image the ice-bed interface with sufficiently high resolution to infer changes in bed geometry over time. This is largely due to hardware limitations in the radar systems used in glaciology which typically support an inadequate number of antenna elements. Unlike in towed or airborne radar systems, where spatial resolution can be improved through synthetic aperture processing techniques, the spatial resolution achieved by a stationary array is proportional to the number of real antenna elements deployed. We overcome limitations in the number of supported antennas by integrating radio-frequency over fiber (RFoF) hardware, typically used in the communications industry, into existing radar systems such as the autonomous phase-sensitive radio-echo sounder (ApRES), as well as software-defined radios (SDRs). By converting RF signals to optical signals, lossy copper-based coaxial cables is replaced by low-loss fiber optic cables, permitting large separations between receive and transmit elements without significant signal attenuation during transmission. Further, the low cost, high switching speeds, and large number of output channels provided by fiber optic switches allows for a cost-effective way to rapidly cycle through 100s of antenna elements using a single radar unit RF input or output port. These modifications allow an ApRES, which traditionally supports up to 8 receive and 8 transmit antennas, to handle 100s of antennas on both the receive and transmit side, offering significant improvements in imaging capabilities. Such a system could support advanced imaging geometries capable of 3D time-lapse monitoring of englacial and subglacial processes, such as seasonal hydrology, subglacial erosion, isostatic rebound, and the evolution of sub-ice shelf features. We demonstrate these imaging capabilities through modelling and initial field results using our modified ApRES and SDR systems.

How to cite: May, D., Pranis, O., Schroeder, D., Teisberg, T., Maayah, S., Morgan, A., Rutherford, Z., Tovar, G., and Hollberg, L.: Multi-Offset Imaging of Bed Topography Using Radio Frequency over Fiber Radar Arrays: Modelling and Initial Field Results, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13161, https://doi.org/10.5194/egusphere-egu25-13161, 2025.

In recent years, glacial lake outburst flood (GLOF) hazards in the Himalayan region have garnered considerable attention. The expansion of glacial lakes and the corresponding increase in volume play major roles in the initiation of GLOFs. Due to the lack of systematic assessments and the challenges associated with conducting field surveys, communities living downstream face significant risks from potential GLOFs. Accurate volume estimation of glacial lakes is crucial for calculating outburst flood peak discharge and simulating flood evolution. However, in-situ bathymetry-derived volume estimations are limited to only a few glacial lakes. Consequently, earlier studies have relied on volume-area empirical relations, which have shown substantial discrepancies. In this study, we surveyed four glacial lakes—Kya Tso Lake (KTL), Panchi Nala Lake (PNL), Gepang Gath Lake (GGL), and Samudri Tapu Lake (STL)—located in the Chandrabhaga basin, western Himalaya. Among these, GGL and STL are reported as potentially dangerous glacial lakes (PDGLs) due to their rapid expansion and risk of future bursts. In-situ depth measurements were conducted using an echo sounder mounted on an unmanned surface vehicle (USV) and portable inflatable kayak. The lake basin morphologies were modelled using triangulated irregular networks (TINs). We compared the bathymetry-derived lake volumes with volumes estimated using commonly used empirical equations. The results revealed maximum depths of 16 m, 10 m, 46 m, and 59 m for KTL, PNL, GGL, and STL, with corresponding storage capacities of 0.89 × 10⁶ m³, 0.44 × 10⁶ m³, 24.12 × 10⁶ m³, and 24.69 × 10⁶ m³, respectively. Substantial discrepancies (± 47-309%) were observed between volumes derived using existing empirical equations and those obtained through in-situ bathymetry for all four lakes. None of the commonly used equations produced similar volume with in-situ observations. Despite several challenges during the USV survey, like noise from variable sound penetration under different turbidity, limited telemetry, wind, boat speed relative to water depth, and floating ice on lake, this study provides valuable in-situ bathymetric data for future modelling and hazard assessment of rapidly expanding PDGLs in the region. The present study emphasizes the need for more robust, in-situ-based bathymetric datasets of glacial lakes to develop an empirical equation with better applicability.

How to cite: Das, S. and Ramsankaran, R.: In-Situ Bathymetry and Volume Estimation of Glacial Lakes in Western Himalaya, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14977, https://doi.org/10.5194/egusphere-egu25-14977, 2025.

Glacier surges are dramatic increases in glacial ice flow velocity occurring over short periods of time (months to years), which can lead to rapid advance of the ice front and trigger hazardous outburst flooding in local areas. Direct measurements of the basal hydrology and internal dynamics of surging glaciers are sparse, due to the limitations of wired instrumentation and the unpredictability of surge timing. Consequently, the causes of surge events are poorly understood, and we are unable to accurately predict their occurrence.

We have developed a borehole instrument, the sausage-shaped "Cryowurst", which can wirelessly transmit measurements of temperature, electrical conductivity, pressure and tilt within and beneath a glacier to the surface over a period of multiple years. These sensors allow us to directly measure the hydrological conditions and kinematics of ice deformation, over longer time periods than is currently possible with wired instrumentation due to cable breakage.

We installed a vertical string of four Cryowursts 20-50m apart in a hot-water-drilled borehole in Dän Zhùr (Donjek Glacier), a surging glacier in the Yukon territory of Canada, which is predicted to surge before 2027. We present preliminary data on the basal hydrology and internal kinematics of the glacier, which were transmitted through up to 170m of ice, and received at a solar-powered and satellite-enabled receiving station on the glacier surface. Based on recent testing, there is potential for these instruments to transmit data continuously over multiple years, capturing novel information about the causes and consequences of glacier surging.

How to cite: Craw, L., Prior-Jones, M., Dow, C., Main, B., Hawkins, J., Alnader, H., Rahn, S. M., and Copeland, L.: Cryowurst: a wireless borehole instrument for observing hydrology and ice kinematics in surging glaciers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16146, https://doi.org/10.5194/egusphere-egu25-16146, 2025.

Fracture-induced ice shelf instability is a critical contributor to uncertainties in sea level projections, which are central to global flood mitigation planning. While the occurrence of ice fracturing at critical stress thresholds is well-documented, the mechanisms governing fracture timing, rate, and orientation remain poorly understood, particularly across ice shelves with varying ice properties and provenance. Observations on the Brunt Ice Shelf reveal unique fracture behaviours, where rifts deviate from their stress-predicted pathways to avoid blocks of meteoric ice, and preferentially fracture through thinner marine ice. The speed of propagation is also influenced by these differences in ice type.   

To improve our understanding of these fracture dynamics, a 37 m firn core through thin, marine-based ice was collected in 2024 on the Brunt Ice Shelf. This core provides a high-resolution record of precipitation and climate changes over the past 40 years, with saline layers at the base. Biogenic species within the core trace variations in summer sea ice extent and proximity to open water, including the A-81 calving in 2023, while an increasing prevalence of melt layers highlights a rise in surface melt. By integrating fracture toughness measurements from layers with varying melt and accumulation conditions, we demonstrate how climatic and environmental shifts could influence ice shelf susceptibility to fracture propagation.

How to cite: Pearce, E., Marsh, O., Thomas, L., Brisbourne, A., Mitchell, T., Humby, J., Tetzner, D., Jones, M., Rawatlal, M., Miller, S., and King, A.: Surface melt driven changes to ice properties for a marine-based ice shelf and the influence on fracture propagation: Insights from a core on the Brunt Ice Shelf, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1493, https://doi.org/10.5194/egusphere-egu25-1493, 2025.

Ice streams are river-like features of ice sheets that move much faster than the surrounding, ice. This contrast in velocity (100s m/yr vs 10s m/yr) results from ice flow being dominated by basal sliding with a fully temperate bed within ice streams, whereas ice is sliding little or not at all outside, where the bed is below the melting point. Here, we present initial results from an ERC-funded project, PHAST, which seeks to unravel the physics driving ice stream formation and dynamics. As part of this project, we seek to characterize observationally the onset of basal sliding at cold/temperate basal transition at an easily accessible alpine glacier (Grenzgletscher). Previous research has found a cold bed in the accumulation zone and a temperate bed in the ablation zone. However, the location of the cold/temperate basal transition is not known. Using a micro vibrator Elvis 7 (p-wave generator) we collected two active seismic profiles at a 3720 m high plateau on the Grenzgletscher; one parallel (250 m) and one (325 m) perpendicular to ice flow. The parallel profile shows a surprising lack of structure below the 328m deep ice-bed contact, suggesting it is likely to be bedrock. However, at the downstream end of the profile there is some stratification, which could be eroded sediments. As there is no polarity reversal at the ice-bed contact we find no indication of water at the bed. These initial results suggest that the cold/temperate basal transition is located further downstream. However, further analysis of this data, alongside passive seismics and ground-penetrating radar data, will help us identify the transition with more confidence – assisting a drilling campaign to be undertaken in 2026.

How to cite: Falcini, F., Hofstede, C., Eisen, O., and Mantelli, E.: Ice-bed interface conditions in the accumulation zone of the Grenzgletscher, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19748, https://doi.org/10.5194/egusphere-egu25-19748, 2025.