Journal: Journal of Glaciology

Abbreviation

J Glaciol

Publisher

Cambridge University Press

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ISSN

0022-1430
1727-5652

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Publications 1 - 10 of 33
  • Definition, formation and rupture mechanisms of water pockets in alpine glaciers: Insights from an updated inventory for the Swiss Alps
    Item type: Journal Article
    Ogier, Christophe; Fischer, Mauro; Werder, Mauro; et al. (2025)
    Journal of Glaciology
    The term 'water pocket' describes invisible en- and subglacial water reservoirs that can cause sudden glacial outburst floods. However, there is currently no consensus on its definition and the formation and rupture mechanisms of water pockets remain poorly understood. This study aims to understand the mechanisms behind water pocket outburst floods (WPOFs) from alpine glaciers by analyzing their spatial and temporal distribution, pre-event meteorological conditions and the glacio-geomorphic features of the glaciers from which the floods originate. To this end, we updated an inventory of known WPOFs in the Swiss Alps to 91 events from 37 individual glaciers. Most WPOFs occurred between June and September, likely linked to meltwater input. Meteorological data indicate anomalously high temperatures during the days preceding most events and heavy precipitation on 25% of days for which WPOFs occur, indicating that water pockets typically rupture during periods of high water input. We propose four mechanisms of water pocket formation: temporary subglacial channel blockage (which is the mechanism suggested most often for our inventory), hydraulic barriers, water-filled crevasses and accumulation of liquid water behind barriers of cold ice (thermal barriers). Overall, our analysis highlights the challenge of understanding WPOFs due to the subsurface nature of water pockets, emphasizing the need for field-based research to improve their detection and monitoring.
  • Subglacial cavity collapses on Swiss glaciers: Spatiotemporal distribution and mass loss contribution
    Item type: Journal Article
    Hösli, Leo; Ogier, Christophe; Bauder, Andreas; et al. (2025)
    Journal of Glaciology
    Glacier collapse features, linked to subglacial cavities, are increasingly common on retreating Alpine glaciers. These features are hypothesized to result from glacier downwasting and subsurface ablation processes but the understanding regarding their distribution, formation and contribution to glacier mass loss remains limited. We present a Swiss-wide inventory of 223 collapse features observed over the past 50 years, revealing a sharp increase in their occurrence since the early 2000s. Using high-resolution digital elevation models, we derive a relationship between collapse feature area and ice ablation and estimate the Swiss-wide contribution of collapse features to glacier mass loss to be $19.8\times 10<^>6\,\text{m}<^>3$ of ice between 1971 and 2023. Based on extensive observations at Rhonegletscher, including surface displacement, ground-penetrating radar and drone-based elevation models, we quantify subsurface ablation rates of up to 27 cm d-1 and provide a detailed description of the collapse processes. We propose that glacier downwasting, enhanced energy supply through subglacial conduits and locally increased basal melt are key components to subglacial cavity growth. Our results highlight the importance of collapse features in the ongoing retreat of Alpine glaciers, stressing the need for further research to understand their formation and long-term implications for glacier dynamics under climate change.
  • Limited impact of climate forcing products on future glacier evolution in Scandinavia and Iceland
    Item type: Journal Article
    Compagno, Loris; Zekollari, Harry; Huss, Matthias; et al. (2021)
    Journal of Glaciology
    Due to climate change, worldwide glaciers are rapidly declining. The trend will continue into the future, with consequences for sea level, water availability and tourism. Here, we assess the future evolution of all glaciers in Scandinavia and Iceland until 2100 using the coupled surface mass-balance ice-flow model GloGEMflow. The model is initialised with three distinct past climate data products (E-OBS, ERA-I, ERA-5), while future climate is prescribed by both global and regional climate models (GCMs and RCMs), in order to analyze their impact on glacier evolution. By 2100, we project Scandinavian glaciers to lose between 67 ± 18% and 90 ± 7% of their present-day (2018) volume under a low (RCP2.6) and a high (RCP8.5) emission scenario, respectively. Over the same period, losses for Icelandic glaciers are projected to be between 43 ± 11% (RCP2.6) and 85 ± 7% (RCP8.5). The projected evolution is only little impacted by both the choice of climate data products used in the past and the spatial resolution of the future climate projections, with differences in the ice volume remaining by 2100 of 7 and 5%, respectively. This small sensitivity is attributed to our model calibration strategy that relies on observed glacier-specific mass balances and thus compensates for differences between climate forcing products.
  • The generalized Clapeyron equation and its application to confined ice growth
    Item type: Journal Article
    Style, Robert; Gerber, Dominic; Rempel, Alan W.; et al. (2023)
    Journal of Glaciology
    Most theoretical descriptions of stresses induced by freezing are rooted in the (generalized) Clapeyron equation, which predicts the pressure that a solid can exert as it cools below its melting temperature. This equation is central for topics ranging beyond glaciology to geomorphology, civil engineering, food storage and cryopreservation. However, it has inherent limitations, requiring isotropic solid stresses and conditions near bulk equilibrium. Here, we examine when the Clapeyron equation is applicable by providing a rigorous derivation that details all assumptions. We demonstrate the natural extension for anisotropic stress states, and we show how the temperature and pressure ranges for validity depend on well-defined material properties. Finally, we demonstrate how the range of applicability of the (linear) Clapeyron equation can be extended by adding higher-order terms, yielding results that are in good agreement with experimental data for the pressure melting of ice.
  • Capillary suction across the soil-snow interface as a mechanism for the formation of wet basal layers under gliding snowpacks
    Item type: Journal Article
    Lombardo, Michael; Fees, Amelie; Udke, Annegret; et al. (2025)
    Journal of Glaciology
    Capillary suction across the soil-snow interface is a possible mechanism for the formation of wet basal snow layers, which are necessary for snow gliding and glide-snow avalanches. However, little is known about the conditions under which this process occurs. We investigated capillary suction across the soil-snow interface considering realistic snow and soil properties. Snow properties were determined from snow profiles and soil properties were determined from field measurements of liquid water content, matric potential, soil texture and bulk density for 40 alpine soils in Davos, Switzerland, as well as a field site in the region (Seewer Berg) with glide-snow avalanche activity. For the alpine soils investigated here, the results show that capillary flow from the soil to the snow is possible for realistic snow properties but requires a soil saturation of similar to 90% or higher at the soil surface. When comparing the 90% saturation threshold to field measurements, the results suggest that capillary suction across the soil-snow interface is unlikely to contribute significantly to the formation of wet basal layers on Seewer Berg. These results are also relevant for soil and snow hydrology, where water transport across the soil-snow interface is important and understudied.
  • Deep learning speeds up ice flow modelling by several orders of magnitude
    Item type: Journal Article
    Jouvet, Guillaume; Cordonnier, Guillaume; Kim, Byungsoo; et al. (2022)
    Journal of Glaciology
    This paper introduces the Instructed Glacier Model (IGM) – a model that simulates ice dynamics, mass balance and its coupling to predict the evolution of glaciers, icefields or ice sheets. The nov elty of IGM is that it models the ice flow by a Convolutional Neural Network, which is trained from data generated with hybrid SIA + SSA or Stokes ice flow models. By doing so, the most com putationally demanding model component is substituted by a cheap emulator. Once trained with representative data, we demonstrate that IGM permits to model mountain glaciers up to 1000 × faster than Stokes ones on Central Processing Units (CPU) with fidelity levels above 90% in terms of ice flow solutions leading to nearly identical transient thickness evolution. Switching to the GPU often permits additional significant speed-ups, especially when emulating Stokes dynamics or/and modelling at high spatial resolution. IGM is an open-source Python code which deals with two-dimensional (2-D) gridded input and output data. Together with a companion library of trained ice flow emulators, IGM permits user-friendly, highly efficient and mechanically state of-the-art glacier and icefields simulations
  • Avalanche dynamics. Review of experiments and theoretical models of flow and powder snow avalanches
    Item type: Journal Article
    Scheiwiller, Thomas; Hutter, Kolumban (1983)
    Journal of Glaciology
    The paper of which this is an extended abstract reviews theoretical formulations for flow and airborne powder-snow avalanches. First powder-snow avalanches are considered as plane turbulent gravity currents. Then we propose a two-phase model describing powder-snow avalanches as turbulent binary mixtures of snow granules and air. An analogy is postulated between flow avalanches and the rapid shear flow of granular materials which leads to a non-polar continuum with microstructure taking into account the fluctuation energy of the snow granules.
  • Improved representation of laminar and turbulent sheet flow in subglacial drainage models
    Item type: Journal Article
    Hill, Tim; Flowers, Gwenn E.; Hoffman, Matthew J.; et al. (2024)
    Journal of Glaciology
    Subglacial hydrology models struggle to reproduce seasonal drainage patterns that are consistent with observed subglacial water pressures and surface velocities. We modify the standard sheet-flow parameterization within a coupled sheet–channel subglacial drainage model to smoothly transition between laminar and turbulent flow based on the locally computed Reynolds number in a physically consistent way (the “transition” model). We compare the transition model to standard laminar and turbulent models to assess the role of the sheet-flow parameterization in reconciling observed and modelled water pressures under idealized and realistic forcing. Relative to the turbulent model, the laminar and transition models improve seasonal simulations by increasing winter water pressure and producing a more prominent late-summer water pressure minimum. In contrast to the laminar model, the transition model remains consistent with its own internal assumptions across all flow regimes. Based on the internal consistency of the transition model and its improved performance relative to the standard turbulent model, we recommend its use for transient simulations of subglacial drainage.
  • Crack propagation speeds in weak snowpack layers
    Item type: Journal Article
    Bergfeld, Bastian; van Herwijnen, Alec; Bobillier, Grégoire; et al. (2022)
    Journal of Glaciology
    For the release of a slab avalanche, crack propagation within a weak snowpack layer below a cohesive snow slab is required. As crack speed measurements can give insight into underlying processes, we analysed three crack propagation events that occurred in similar snowpacks and covered all scales relevant for avalanche release. For the largest scale, up to 400 m, we estimated crack speed from an avalanche movie; for scales between 5 and 25 m, we used accelerometers placed on the snow surface and for scales below 5 m, we performed a propagation saw test. The mean crack speeds ranged from 36 ± 6 to 49 ± 5 m s−1, and did not exhibit scale dependence. Using the discrete element method and the material point method, we reproduced the measured crack speeds reasonably well, in particular the terminal crack speed observed at smaller scales. Finally, we used a finite element model to assess the speed of different elastic waves in a layered snowpack. Results suggest that the observed cracks propagated as mixed mode closing cracks and that the flexural wave of the slab is responsible for the energy transfer to the crack tip.
  • Electrical resistivity soundings of glacier beds: A test study on Grubengletscher, Wallis, Swiss Alps
    Item type: Journal Article
    Haeberli, Wilfried; Fisch, Werner (1984)
    Journal of Glaciology
    Electrical resistivity sounding, using electrodes which are lowered directly to the ice–rock interface in bore holes, is proposed as a technique for studying the exact position of glacier beds, as well as their lithological characteristics. A test study is described on Grubengletscher, a partially cold Alpine glacier in Switzerland. Results of soundings along a 400m long profile indicate that previous depth determinations, based on radio echo-soundings, were in general accurate to within less than 5% of the actual ice thickness. The results also show that the glacier rests on non-consolidated sediments of considerable thickness. The proposed method could add substantial information about glacier sliding and glacier erosion, if applied alongside conventional deep drilling projects.
Publications 1 - 10 of 33