Articles | Volume 12, issue 8
https://doi.org/10.5194/tc-12-2609-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-12-2609-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| Highlight paper
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14 Aug 2018
Research article | Highlight paper |
| 14 Aug 2018
| 14 Aug 2018
Channelized, distributed, and disconnected: subglacial drainage under a valley glacier in the Yukon
Department of Earth, Ocean and Atmospheric Sciences, University of
British Columbia, 2207 Main Mall, Vancouver, BC, Canada
Christian Schoof
Department of Earth, Ocean and Atmospheric Sciences, University of
British Columbia, 2207 Main Mall, Vancouver, BC, Canada
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Camilo Andrés Rada Giacaman and Christian Schoof
The Cryosphere, 17, 761–787, https://doi.org/10.5194/tc-17-761-2023, https://doi.org/10.5194/tc-17-761-2023, 2023
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Water flowing at the base of glaciers plays a crucial role in controlling the speed at which glaciers move and how glaciers react to climate. The processes happening below the glaciers are extremely hard to observe and remain only partially understood. Here we provide novel insight into the subglacial environment based on an extensive dataset with over 300 boreholes on an alpine glacier in the Yukon Territory. We highlight the importance of hydraulically disconnected regions of the glacier bed.
Maryam Zarrinderakht, Christian Schoof, and Anthony Peirce
The Cryosphere, 18, 3841–3856, https://doi.org/10.5194/tc-18-3841-2024, https://doi.org/10.5194/tc-18-3841-2024, 2024
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The objective of the study is to understand the interactions between surface and basal crevasses by conducting a stability analysis and addressing the implications of the findings for potential calving laws. The study's findings indicate that, while the propagation of one crack in the case of two aligned surface and basal crevasses does not significantly reinforce the propagation of the other, the presence of multiple crevasses on one side enhances stability and decreases crack propagation.
Maryam Zarrinderakht, Christian Schoof, and Thomas Zwinger
EGUsphere, https://doi.org/10.5194/egusphere-2023-807, https://doi.org/10.5194/egusphere-2023-807, 2023
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We used a model to study how crevasses propagate in ice shelves. Our model combines a viscous model and a fracture mechanics model. We studied periodic crevasses on an ice shelf being stretched. We show that existing models based only on stress cannot fully explain how crevasses grow and lead to iceberg calving. This model can be a useful tool to train a low-dimensional representation calving law for an ice sheet model.
Camilo Andrés Rada Giacaman and Christian Schoof
The Cryosphere, 17, 761–787, https://doi.org/10.5194/tc-17-761-2023, https://doi.org/10.5194/tc-17-761-2023, 2023
Short summary
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Water flowing at the base of glaciers plays a crucial role in controlling the speed at which glaciers move and how glaciers react to climate. The processes happening below the glaciers are extremely hard to observe and remain only partially understood. Here we provide novel insight into the subglacial environment based on an extensive dataset with over 300 boreholes on an alpine glacier in the Yukon Territory. We highlight the importance of hydraulically disconnected regions of the glacier bed.
Maryam Zarrinderakht, Christian Schoof, and Anthony Peirce
The Cryosphere, 16, 4491–4512, https://doi.org/10.5194/tc-16-4491-2022, https://doi.org/10.5194/tc-16-4491-2022, 2022
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Iceberg calving is the reason for more than half of mass loss in both Greenland and Antarctica and indirectly contributes to sea-level rise. Our study models iceberg calving by linear elastic fracture mechanics and uses a boundary element method to compute crack tip propagation. This model handles the contact condition: preventing crack faces from penetrating into each other and enabling the derivation of calving laws for different forms of hydrological forcing.
Christian Schoof
The Cryosphere, 14, 3175–3194, https://doi.org/10.5194/tc-14-3175-2020, https://doi.org/10.5194/tc-14-3175-2020, 2020
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Glacier lake outburst floods are major glacial hazards in which ice-dammed reservoirs rapidly drain, often in a recurring fashion. The main flood phase typically involves a growing channel being eroded into ice by water flow. What is poorly understood is how that channel first comes into being. In this paper, I investigate how an under-ice drainage system composed of small, naturally occurring voids can turn into a channel and how this can explain the cyclical behaviour of outburst floods.
Marianne Haseloff, Christian Schoof, and Olivier Gagliardini
The Cryosphere, 12, 2545–2568, https://doi.org/10.5194/tc-12-2545-2018, https://doi.org/10.5194/tc-12-2545-2018, 2018
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The widths of the Siple Coast ice streams evolve on decadal to centennial timescales. We investigate how the rate of thermally driven ice stream widening depends on heat dissipation in the ice stream margin and at the bed, and on the inflow of cold ice from the ice ridge. As determining the migration rate requires resolving heat transfer processes on very small scales, we derive a parametrization of the migration rate in terms of parameters that are available from large-scale model outputs.
Christian Schoof, Andrew D. Davis, and Tiberiu V. Popa
The Cryosphere, 11, 2283–2303, https://doi.org/10.5194/tc-11-2283-2017, https://doi.org/10.5194/tc-11-2283-2017, 2017
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We show mathematically and computationally how discharge of ice from ocean-terminating glaciers is controlled by a combination of different forces acting on ice near the grounding line of a glacier and how that combination of forces is affected by the process of iceberg formation, which limits the length of floating ice tongues extending in front of the glacier. We show that a deeper fjord may lead to a longer ice tongue providing greater drag on the glacier, slowing the rate of ice discharge.
Ian J. Hewitt and Christian Schoof
The Cryosphere, 11, 541–551, https://doi.org/10.5194/tc-11-541-2017, https://doi.org/10.5194/tc-11-541-2017, 2017
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Many glaciers contain ice both below and at the melting temperature. Predicting the evolution of temperature and water content in such ice masses is important because they exert a strong control on the flow of the ice. We present two new models to calculate these quantities, demonstrate a number of example numerical calculations, and compare the results with existing methods. The novelty of the new methods is the inclusion of gravity-driven water transport within the ice.
Alexander A. Robel, Christian Schoof, and Eli Tziperman
The Cryosphere, 10, 1883–1896, https://doi.org/10.5194/tc-10-1883-2016, https://doi.org/10.5194/tc-10-1883-2016, 2016
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Portions of the Antarctic Ice Sheet edge that rest on upward-sloping beds have the potential to collapse irreversibly and raise global sea level. Using a numerical model, we show that changes in the slipperiness of sediments beneath fast-flowing ice streams can cause them to persist on upward-sloping beds for hundreds to thousands of years before reversing direction. This type of behavior is important to consider as a possibility when interpreting observations of ongoing ice sheet change.
C. Schoof, C. A Rada, N. J. Wilson, G. E. Flowers, and M. Haseloff
The Cryosphere, 8, 959–976, https://doi.org/10.5194/tc-8-959-2014, https://doi.org/10.5194/tc-8-959-2014, 2014
A. H. Jarosch, C. G. Schoof, and F. S. Anslow
The Cryosphere, 7, 229–240, https://doi.org/10.5194/tc-7-229-2013, https://doi.org/10.5194/tc-7-229-2013, 2013
Related subject area
Discipline: Glaciers | Subject: Glacier Hydrology
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Characterizing sub-glacial hydrology using radar simulations
Velocity variations and hydrological drainage at Baltoro Glacier, Pakistan
Seasonal to decadal dynamics of supraglacial lakes on debris-covered glaciers in the Khumbu region, Nepal
A conceptual model for glacial lake bathymetric distribution
The evolution of isolated cavities and hydraulic connection at the glacier bed – Part 1: Steady states and friction laws
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Geophysical constraints on the properties of a subglacial lake in northwest Greenland
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Lucas Zeller, Daniel McGrath, Scott W. McCoy, and Jonathan Jacquet
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The Cryosphere, 17, 4817–4836, https://doi.org/10.5194/tc-17-4817-2023, https://doi.org/10.5194/tc-17-4817-2023, 2023
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The subglacial drainage of meltwater plays a major role in regulating glacier and ice sheet flow. In this paper, I construct and solve a mathematical model that describes how connections are made within the subglacial drainage system. This will aid future efforts to predict glacier response to surface melt supply.
Tim Hill and Christine F. Dow
The Cryosphere, 17, 2607–2624, https://doi.org/10.5194/tc-17-2607-2023, https://doi.org/10.5194/tc-17-2607-2023, 2023
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Water flow across the surface of the Greenland Ice Sheet controls the rate of water flow to the glacier bed. Here, we simulate surface water flow for a small catchment on the southwestern Greenland Ice Sheet. Our simulations predict significant differences in the form of surface water flow in high and low melt years depending on the rate and intensity of surface melt. These model outputs will be important in future work assessing the impact of surface water flow on subglacial water pressure.
Amy Jenson, Mark Skidmore, Lucas Beem, Martin Truffer, and Scott McCalla
EGUsphere, https://doi.org/10.5194/egusphere-2023-792, https://doi.org/10.5194/egusphere-2023-792, 2023
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Water in some glacier environments contains salt which increases the density of the fluid and decreases the freezing point of the fluid. As a result, hypersaline lakes can exist in places where freshwater cannot and can contain unique microbiological communities. We model the flow of saline fluid from a subglacial lake through a channel at the glacier bed. The results suggest that fluid with higher salinity reach higher discharge rates compared to fresh water due to increased fluid density.
Elena Shevnina, Miguel Potes, Timo Vihma, Tuomas Naakka, Pankaj Ramji Dhote, and Praveen Kumar Thakur
The Cryosphere, 16, 3101–3121, https://doi.org/10.5194/tc-16-3101-2022, https://doi.org/10.5194/tc-16-3101-2022, 2022
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The evaporation over an ice-free glacial lake was measured in January 2018, and the uncertainties inherent to five indirect methods were quantified. Results show that in summer up to 5 mm of water evaporated daily from the surface of the lake located in Antarctica. The indirect methods underestimated the evaporation over the lake's surface by up to 72 %. The results are important for estimating the evaporation over polar regions where a growing number of glacial lakes have recently been evident.
Fabiola Banfi and Carlo De Michele
The Cryosphere, 16, 1031–1056, https://doi.org/10.5194/tc-16-1031-2022, https://doi.org/10.5194/tc-16-1031-2022, 2022
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Climate changes require a dynamic description of glaciers in hydrological models. In this study we focus on the local modelling of snow and firn. We tested our model at the site of Colle Gnifetti, 4400–4550 m a.s.l. The model shows that wind erodes all the precipitation of the cold months, while snow is in part conserved between April and September since higher temperatures protect snow from erosion. We also compared modelled and observed firn density, obtaining a satisfying agreement.
Caroline C. Clason, Will H. Blake, Nick Selmes, Alex Taylor, Pascal Boeckx, Jessica Kitch, Stephanie C. Mills, Giovanni Baccolo, and Geoffrey E. Millward
The Cryosphere, 15, 5151–5168, https://doi.org/10.5194/tc-15-5151-2021, https://doi.org/10.5194/tc-15-5151-2021, 2021
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Our paper presents results of sample collection and subsequent geochemical analyses from the glaciated Isfallsglaciären catchment in Arctic Sweden. The data suggest that material found on the surface of glaciers,
cryoconite, is very efficient at accumulating products of nuclear fallout transported in the atmosphere following events such as the Chernobyl disaster. We investigate how this compares with samples in the downstream environment and consider potential environmental implications.
Christophe Ogier, Mauro A. Werder, Matthias Huss, Isabelle Kull, David Hodel, and Daniel Farinotti
The Cryosphere, 15, 5133–5150, https://doi.org/10.5194/tc-15-5133-2021, https://doi.org/10.5194/tc-15-5133-2021, 2021
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Glacier-dammed lakes are prone to draining rapidly when the ice dam breaks and constitute a serious threat to populations downstream. Such a lake drainage can proceed through an open-air channel at the glacier surface. In this study, we present what we believe to be the most complete dataset to date of an ice-dammed lake drainage through such an open-air channel. We provide new insights for future glacier-dammed lake drainage modelling studies and hazard assessments.
Eyjólfur Magnússon, Finnur Pálsson, Magnús T. Gudmundsson, Thórdís Högnadóttir, Cristian Rossi, Thorsteinn Thorsteinsson, Benedikt G. Ófeigsson, Erik Sturkell, and Tómas Jóhannesson
The Cryosphere, 15, 3731–3749, https://doi.org/10.5194/tc-15-3731-2021, https://doi.org/10.5194/tc-15-3731-2021, 2021
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We present a unique insight into the shape and development of a subglacial lake over a 7-year period, using repeated radar survey. The lake collects geothermal meltwater, which is released in semi-regular floods, often referred to as jökulhlaups. The applicability of our survey approach to monitor the water stored in the lake for a better assessment of the potential hazard of jökulhlaups is demonstrated by comparison with independent measurements of released water volume during two jökulhlaups.
Ross Maguire, Nicholas Schmerr, Erin Pettit, Kiya Riverman, Christyna Gardner, Daniella N. DellaGiustina, Brad Avenson, Natalie Wagner, Angela G. Marusiak, Namrah Habib, Juliette I. Broadbeck, Veronica J. Bray, and Samuel H. Bailey
The Cryosphere, 15, 3279–3291, https://doi.org/10.5194/tc-15-3279-2021, https://doi.org/10.5194/tc-15-3279-2021, 2021
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In the last decade, airborne radar surveys have revealed the presence of lakes below the Greenland ice sheet. However, little is known about their properties, including their depth and the volume of water they store. We performed a ground-based geophysics survey in northwestern Greenland and, for the first time, were able to image the depth of a subglacial lake and estimate its volume. Our findings have implications for the thermal state and stability of the ice sheet in northwest Greenland.
Hannah R. Field, William H. Armstrong, and Matthias Huss
The Cryosphere, 15, 3255–3278, https://doi.org/10.5194/tc-15-3255-2021, https://doi.org/10.5194/tc-15-3255-2021, 2021
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The growth of a glacier lake alters the hydrology, ecology, and glaciology of its surrounding region. We investigate modern glacier lake area change across northwestern North America using repeat satellite imagery. Broadly, we find that lakes downstream from glaciers grew, while lakes dammed by glaciers shrunk. Our results suggest that the shape of the landscape surrounding a glacier lake plays a larger role in determining how quickly a lake changes than climatic or glaciologic factors.
Chloé Scholzen, Thomas V. Schuler, and Adrien Gilbert
The Cryosphere, 15, 2719–2738, https://doi.org/10.5194/tc-15-2719-2021, https://doi.org/10.5194/tc-15-2719-2021, 2021
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We use a two-dimensional model of water flow below the glaciers in Kongsfjord, Svalbard, to investigate how different processes of surface-to-bed meltwater transfer affect subglacial hydraulic conditions. The latter are important for the sliding motion of glaciers, which in some cases exhibit huge variations. Our findings indicate that the glaciers in our study area undergo substantial sliding because water is poorly evacuated from their base, with limited influence from the surface hydrology.
Andreas Kellerer-Pirklbauer, Michael Avian, Douglas I. Benn, Felix Bernsteiner, Philipp Krisch, and Christian Ziesler
The Cryosphere, 15, 1237–1258, https://doi.org/10.5194/tc-15-1237-2021, https://doi.org/10.5194/tc-15-1237-2021, 2021
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Present climate warming leads to glacier recession and formation of lakes. We studied the nature and rate of lake evolution in the period 1998–2019 at Pasterze Glacier, Austria. We detected for instance several large-scale and rapidly occurring ice-breakup events from below the water level. This process, previously not reported from the European Alps, might play an important role at alpine glaciers in the future as many glaciers are expected to recede into valley basins allowing lake formation.
Christian Schoof
The Cryosphere, 14, 3175–3194, https://doi.org/10.5194/tc-14-3175-2020, https://doi.org/10.5194/tc-14-3175-2020, 2020
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Glacier lake outburst floods are major glacial hazards in which ice-dammed reservoirs rapidly drain, often in a recurring fashion. The main flood phase typically involves a growing channel being eroded into ice by water flow. What is poorly understood is how that channel first comes into being. In this paper, I investigate how an under-ice drainage system composed of small, naturally occurring voids can turn into a channel and how this can explain the cyclical behaviour of outburst floods.
Samuel J. Cook, Poul Christoffersen, Joe Todd, Donald Slater, and Nolwenn Chauché
The Cryosphere, 14, 905–924, https://doi.org/10.5194/tc-14-905-2020, https://doi.org/10.5194/tc-14-905-2020, 2020
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This paper models how water flows beneath a large Greenlandic glacier and how the structure of the drainage system it flows in changes over time. We also look at how this affects melting driven by freshwater plumes at the glacier front, as well as the implications for glacier flow and sea-level rise. We find an active drainage system and plumes exist year round, contradicting previous assumptions and suggesting more melting may not slow the glacier down, unlike at other sites in Greenland.
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Short summary
We analyse a large glacier borehole pressure dataset and provide a holistic view of the observations, suggesting a consistent picture of the evolution of the subglacial drainage system. Some aspects are consistent with the established understanding and others ones are not. We propose that most of the inconsistencies arise from the capacity of some areas of the bed to become hydraulically isolated. We present an adaptation of an existing drainage model that incorporates this phenomena.
We analyse a large glacier borehole pressure dataset and provide a holistic view of the...
