Articles | Volume 12, issue 3
https://doi.org/10.5194/tc-12-955-2018
© 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-12-955-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
21 Mar 2018
Research article |
| 21 Mar 2018
| 21 Mar 2018
Meltwater storage in low-density near-surface bare ice in the Greenland ice sheet ablation zone
Department of Geography, University of California-Los Angeles, CA
90095, USA
Laurence C. Smith
Department of Geography, University of California-Los Angeles, CA
90095, USA
Asa K. Rennermalm
Department of Geography, Rutgers, The State University of New Jersey,
Piscataway, NJ 08854, USA
Clément Miège
Department of Geography, University of Utah, Salt Lake City, UT, USA
Lincoln H. Pitcher
Department of Geography, University of California-Los Angeles, CA
90095, USA
Jonathan C. Ryan
Department of Geography, University of California-Los Angeles, CA
90095, USA
Institute at Brown for Environment and Society, Brown University,
Providence, RI, USA
Kang Yang
School of Geographical and Oceanographic Sciences, Nanjing University,
Nanjing 210023, China
Joint Center for Global Change Studies, Beijing 100875, China
Sarah W. Cooley
Department of Geography, University of California-Los Angeles, CA
90095, USA
Dept. of Earth, Environmental and Planetary Sciences, Brown
University, Providence, RI 02912, USA
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Discrete Global Grid systems, or DGGs, are digital frameworks that help us organize information about our planet. Although scientists have used DGGs in areas like weather and nature, using them in the water cycle has been challenging because some core datasets are missing. We created a way to generate these datasets. We then developed the datasets in the Amazon Basin, which plays an important role in our planet's climate. These datasets may help us improve our water cycle models.
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In situ measurements of meltwater discharge through supraglacial stream networks are rare. The unprecedentedly long record of discharge captures diurnal and seasonal variability. Two major findings are (1) a change in the timing of peak discharge through the melt season that could impact meltwater delivery in the subglacial system and (2) though the primary driver of stream discharge is shortwave radiation, longwave radiation and turbulent heat fluxes play a major role during high-melt episodes.
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We apply first-principle hydrology models designed for global river routing to route flows hourly through 10 000 individual supraglacial channels in Greenland. Our results uniquely show the role of process controls (network density, hillslope flow, channel friction) on routed meltwater. We also confirm earlier suggestions that large channels do not dewater overnight despite the shutdown of runoff and surface mass balance runoff being mistimed and overproducing runoff, as validated in situ.
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We measured sunlight transmitted into glacier ice to improve models of glacier ice melt and satellite measurements of glacier ice surfaces. We found that very small concentrations of impurities inside the ice increase absorption of sunlight, but the amount was small enough to enable an estimate of ice absorptivity. We confirmed earlier results that the absorption minimum is near 390 nm. We also found that a layer of highly reflective granular "white ice" near the surface reduces transmittance.
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A high-resolution spatially lumped hydrologic surface routing model is proposed to simulate meltwater transport over bare ice surfaces. In an ice-covered catchment, meltwater is routed by slow interfluve flow (~10−3–10−4 m s−1) followed by fast open-channel flow (~10−1 m s−1). Seasonal evolution of supraglacial stream-river networks substantially alters the magnitude and timing of moulin discharge with implications for subglacial hydrology and ice dynamics.
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Discrete Global Grid systems, or DGGs, are digital frameworks that help us organize information about our planet. Although scientists have used DGGs in areas like weather and nature, using them in the water cycle has been challenging because some core datasets are missing. We created a way to generate these datasets. We then developed the datasets in the Amazon Basin, which plays an important role in our planet's climate. These datasets may help us improve our water cycle models.
Baptiste Vandecrux, Robert S. Fausto, Jason E. Box, Federico Covi, Regine Hock, Åsa K. Rennermalm, Achim Heilig, Jakob Abermann, Dirk van As, Elisa Bjerre, Xavier Fettweis, Paul C. J. P. Smeets, Peter Kuipers Munneke, Michiel R. van den Broeke, Max Brils, Peter L. Langen, Ruth Mottram, and Andreas P. Ahlstrøm
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We map and quantify surface rivers and lakes at Humboldt Glacier to examine seasonal evolution and provide new insights of network configuration and behaviour. A widespread supraglacial drainage network exists, expanding up the glacier as seasonal runoff increases. Large interannual variability affects the areal extent of this network, controlled by high- vs. low-melt years, with late summer network persistence likely preconditioning the surface for earlier drainage activity the following year.
Sarah E. Esenther, Laurence C. Smith, Adam LeWinter, Lincoln H. Pitcher, Brandon T. Overstreet, Aaron Kehl, Cuyler Onclin, Seth Goldstein, and Jonathan C. Ryan
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Meltwater runoff estimates from the Greenland ice sheet contain uncertainty. To better understand ice sheet hydrology, we installed a weather station and river stage sensors along three proglacial rivers in a cold-bedded area of NW Greenland without firn, crevasse, or moulin influence. The first 3 years (2019–2021) of observations have given us a first look at the seasonal and annual weather and hydrological patterns of this understudied region.
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The Cryosphere Discuss., https://doi.org/10.5194/tc-2022-195, https://doi.org/10.5194/tc-2022-195, 2022
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Snow and ice melt driven by solar absorption is enhanced by the presence of light-absorbing particles (LAPs), such as black carbon (BC) and dust. Previous studies have ruled out LAP as an important Greenland's albedo reduction and accelerated mass loss rate factor. However, most simulations only take into consideration LAP direct effects. This study shows that taking into account LAP impact on snow metamorphism leads to albedo reductions 4 to 10 times larger than previously thought.
Rohi Muthyala, Åsa K. Rennermalm, Sasha Z. Leidman, Matthew G. Cooper, Sarah W. Cooley, Laurence C. Smith, and Dirk van As
The Cryosphere, 16, 2245–2263, https://doi.org/10.5194/tc-16-2245-2022, https://doi.org/10.5194/tc-16-2245-2022, 2022
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In situ measurements of meltwater discharge through supraglacial stream networks are rare. The unprecedentedly long record of discharge captures diurnal and seasonal variability. Two major findings are (1) a change in the timing of peak discharge through the melt season that could impact meltwater delivery in the subglacial system and (2) though the primary driver of stream discharge is shortwave radiation, longwave radiation and turbulent heat fluxes play a major role during high-melt episodes.
Colin J. Gleason, Kang Yang, Dongmei Feng, Laurence C. Smith, Kai Liu, Lincoln H. Pitcher, Vena W. Chu, Matthew G. Cooper, Brandon T. Overstreet, Asa K. Rennermalm, and Jonathan C. Ryan
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We apply first-principle hydrology models designed for global river routing to route flows hourly through 10 000 individual supraglacial channels in Greenland. Our results uniquely show the role of process controls (network density, hillslope flow, channel friction) on routed meltwater. We also confirm earlier suggestions that large channels do not dewater overnight despite the shutdown of runoff and surface mass balance runoff being mistimed and overproducing runoff, as validated in situ.
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We measured sunlight transmitted into glacier ice to improve models of glacier ice melt and satellite measurements of glacier ice surfaces. We found that very small concentrations of impurities inside the ice increase absorption of sunlight, but the amount was small enough to enable an estimate of ice absorptivity. We confirmed earlier results that the absorption minimum is near 390 nm. We also found that a layer of highly reflective granular "white ice" near the surface reduces transmittance.
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This study compares hourly supraglacial moulin discharge simulations from three surface meltwater routing models. Results show that these models are superior to simply using regional climate model runoff without routing, but different routing models, different-spatial-resolution DEMs, and parameterized seasonal evolution of supraglacial stream and river networks induce significant variability in diurnal moulin discharges and corresponding subglacial effective pressures.
Baptiste Vandecrux, Michael MacFerrin, Horst Machguth, William T. Colgan, Dirk van As, Achim Heilig, C. Max Stevens, Charalampos Charalampidis, Robert S. Fausto, Elizabeth M. Morris, Ellen Mosley-Thompson, Lora Koenig, Lynn N. Montgomery, Clément Miège, Sebastian B. Simonsen, Thomas Ingeman-Nielsen, and Jason E. Box
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The perennial snow, or firn, on the Greenland ice sheet each summer stores part of the meltwater formed at the surface, buffering the ice sheet’s contribution to sea level. We gathered observations of firn air content, indicative of the space available in the firn to retain meltwater, and find that this air content remained stable in cold regions of the firn over the last 65 years but recently decreased significantly in western Greenland.
Kang Yang, Laurence C. Smith, Leif Karlstrom, Matthew G. Cooper, Marco Tedesco, Dirk van As, Xiao Cheng, Zhuoqi Chen, and Manchun Li
The Cryosphere, 12, 3791–3811, https://doi.org/10.5194/tc-12-3791-2018, https://doi.org/10.5194/tc-12-3791-2018, 2018
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A high-resolution spatially lumped hydrologic surface routing model is proposed to simulate meltwater transport over bare ice surfaces. In an ice-covered catchment, meltwater is routed by slow interfluve flow (~10−3–10−4 m s−1) followed by fast open-channel flow (~10−1 m s−1). Seasonal evolution of supraglacial stream-river networks substantially alters the magnitude and timing of moulin discharge with implications for subglacial hydrology and ice dynamics.
Josh Crozier, Leif Karlstrom, and Kang Yang
The Cryosphere, 12, 3383–3407, https://doi.org/10.5194/tc-12-3383-2018, https://doi.org/10.5194/tc-12-3383-2018, 2018
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Understanding ice sheet surface meltwater routing is important for modeling and predicting ice sheet evolution. We determined that bed topography underlying the Greenland Ice Sheet is the primary influence on 1–10 km scale ice surface topography, and on drainage-basin-scale surface meltwater routing. We provide a simple means of predicting the response of surface meltwater routing to changing ice flow conditions and explore the implications of this for subglacial hydrology.
Julienne C. Stroeve, John R. Mioduszewski, Asa Rennermalm, Linette N. Boisvert, Marco Tedesco, and David Robinson
The Cryosphere, 11, 2363–2381, https://doi.org/10.5194/tc-11-2363-2017, https://doi.org/10.5194/tc-11-2363-2017, 2017
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As the sea ice has declined strongly in recent years there has been a corresponding increase in Greenland melting. While both are likely a result of changes in atmospheric circulation patterns that favor summer melt, this study evaluates whether or not sea ice reductions around the Greenland ice sheet are having an influence on Greenland summer melt through enhanced sensible and latent heat transport from open water areas onto the ice sheet.
Dirk van As, Andreas Bech Mikkelsen, Morten Holtegaard Nielsen, Jason E. Box, Lillemor Claesson Liljedahl, Katrin Lindbäck, Lincoln Pitcher, and Bent Hasholt
The Cryosphere, 11, 1371–1386, https://doi.org/10.5194/tc-11-1371-2017, https://doi.org/10.5194/tc-11-1371-2017, 2017
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The Greenland ice sheet melts faster in a warmer climate. The ice sheet is flatter at high elevation, therefore atmospheric warming increases the melt area exponentially. For current climate conditions, we find that the ice sheet shape amplifies the total meltwater generation by roughly 60 %. Meltwater is not stored underneath the ice sheet, as previously found, but it does take multiple days for it to pass through the seasonally developing subglacial drainage channels, moderating discharge.
Jonathan C. Ryan, Alun Hubbard, Marek Stibal, Jason E. Box, and the Dark Snow Project team
The Cryosphere Discuss., https://doi.org/10.5194/tc-2016-204, https://doi.org/10.5194/tc-2016-204, 2016
Preprint withdrawn
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Using digital imagery and broadband albedo acquired by a fixed-wing UAS we classified and measured the albedo of six surface types that dominate the Greenland ablation area and its dark region. We found that the primary control on ablation area albedo is the fractional area of distributed impurities. Although not the darkest surface type observed, the distributed impurities dominate the albedo signal because of their extensive coverage.
C. J. Gleason, L. C. Smith, D. C. Finnegan, A. L. LeWinter, L. H Pitcher, and V. W. Chu
Hydrol. Earth Syst. Sci., 19, 2963–2969, https://doi.org/10.5194/hess-19-2963-2015, https://doi.org/10.5194/hess-19-2963-2015, 2015
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Here, we give a semi-automated processing workflow to extract hydraulic parameters from over 10,000 time-lapse images of the remote Isortoq River in Greenland. This workflow allows efficient and accurate (mean accuracy 79.6%) classification of images following an automated similarity filtering process. We also give an effective width hydrograph (a proxy for discharge) for the Isortoq using this workflow, showing the potential of this workflow for enhancing understanding of remote rivers.
S. E. Moustafa, A. K. Rennermalm, L. C. Smith, M. A. Miller, J. R. Mioduszewski, L. S. Koenig, M. G. Hom, and C. A. Shuman
The Cryosphere, 9, 905–923, https://doi.org/10.5194/tc-9-905-2015, https://doi.org/10.5194/tc-9-905-2015, 2015
J. C. Ryan, A. L. Hubbard, J. E. Box, J. Todd, P. Christoffersen, J. R. Carr, T. O. Holt, and N. Snooke
The Cryosphere, 9, 1–11, https://doi.org/10.5194/tc-9-1-2015, https://doi.org/10.5194/tc-9-1-2015, 2015
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An unmanned aerial vehicle (UAV) equipped with a commercial digital camera enabled us to obtain high-resolution digital images of the calving front of Store glacier, Greenland. The three sorties flown enabled key glaciological parameters to be quantified in sufficient detail to reveal that the terminus of Store glacier is a complex system with large variations in crevasse patterns surface velocities, calving processes, surface elevations and front positions at a daily and seasonal timescale.
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The Cryosphere, 18, 5451–5464, https://doi.org/10.5194/tc-18-5451-2024, https://doi.org/10.5194/tc-18-5451-2024, 2024
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The Cryosphere, 18, 5431–5449, https://doi.org/10.5194/tc-18-5431-2024, https://doi.org/10.5194/tc-18-5431-2024, 2024
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The estimation of the amount of water found within supraglacial lakes is important for understanding how much water is lost from glaciers each year. Here, we develop two new methods for estimating supraglacial lake volume that can be easily applied on a large scale. Furthermore, we compare these methods to two previously developed methods in order to determine when it is best to use each method. Finally, three of these methods are applied to peak melt dates over an area in Northeast Greenland.
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The Cryosphere, 18, 4873–4916, https://doi.org/10.5194/tc-18-4873-2024, https://doi.org/10.5194/tc-18-4873-2024, 2024
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Understanding how glaciers generate sediment and transport it to the ocean is important for understanding ocean ecosystems and developing knowledge of the past cryosphere from marine sediments. This paper presents a new way to simulate sediment transport in rivers below ice sheets and glaciers and quantify volumes and characteristics of sediment that can be used to reveal the hidden record of the subglacial environment for both past and present glacial conditions.
Alexis Caro, Thomas Condom, Antoine Rabatel, Nicolas Champollion, Nicolás García, and Freddy Saavedra
The Cryosphere, 18, 2487–2507, https://doi.org/10.5194/tc-18-2487-2024, https://doi.org/10.5194/tc-18-2487-2024, 2024
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The glacier runoff changes are still unknown in most of the Andean catchments, thereby increasing uncertainties in estimating water availability, especially during the dry season. Here, we simulate glacier evolution and related glacier runoff changes across the Andes between 2000 and 2019. Our results indicate a glacier reduction in 93 % of the catchments, leading to a 12 % increase in glacier melt. These results can be downloaded and integrated with discharge measurements in each catchment.
Chris Pierce, Christopher Gerekos, Mark Skidmore, Lucas Beem, Don Blankenship, Won Sang Lee, Ed Adams, Choon-Ki Lee, and Jamey Stutz
The Cryosphere, 18, 1495–1515, https://doi.org/10.5194/tc-18-1495-2024, https://doi.org/10.5194/tc-18-1495-2024, 2024
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Water beneath glaciers in Antarctica can influence how the ice slides or melts. Airborne radar can detect this water, which looks bright in radar images. However, common techniques cannot identify the water's size or shape. We used a simulator to show how the radar image changes based on the bed material, size, and shape of the waterbody. This technique was applied to a suspected waterbody beneath Thwaites Glacier. We found it may be consistent with a series of wide, flat canals or a lake.
Sheng Dong, Lei Fu, Xueyuan Tang, Zefeng Li, and Xiaofei Chen
The Cryosphere, 18, 1241–1257, https://doi.org/10.5194/tc-18-1241-2024, https://doi.org/10.5194/tc-18-1241-2024, 2024
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Subglacial lakes are a unique environment at the bottom of ice sheets, and they have distinct features in radar echo images that allow for visual detection. In this study, we use machine learning to analyze radar reflection waveforms and identify candidate subglacial lakes. Our approach detects more lakes than known inventories and can be used to expand the subglacial lake inventory. Additionally, this analysis may also provide insights into interpreting other subglacial conditions.
Anna Wendleder, Jasmin Bramboeck, Jamie Izzard, Thilo Erbertseder, Pablo d'Angelo, Andreas Schmitt, Duncan J. Quincey, Christoph Mayer, and Matthias H. Braun
The Cryosphere, 18, 1085–1103, https://doi.org/10.5194/tc-18-1085-2024, https://doi.org/10.5194/tc-18-1085-2024, 2024
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This study analyses the basal sliding and the hydrological drainage of Baltoro Glacier, Pakistan. The surface velocity was characterized by a spring speed-up, summer peak, and autumn speed-up. Snow melt has the largest impact on the spring speed-up, summer velocity peak, and the transition from inefficient to efficient drainage. Drainage from supraglacial lakes contributed to the fall speed-up. Increased summer temperatures will intensify the magnitude of meltwater and thus surface velocities.
Christopher J. L. Wilson, Mark Peternell, Filomena Salvemini, Vladimir Luzin, Frieder Enzmann, Olga Moravcova, and Nicholas J. R. Hunter
The Cryosphere, 18, 819–836, https://doi.org/10.5194/tc-18-819-2024, https://doi.org/10.5194/tc-18-819-2024, 2024
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As the temperature increases within a deforming ice aggregate, composed of deuterium (D2O) ice and water (H2O) ice, a set of meltwater segregations are produced. These are composed of H2O and HDO and are located in conjugate shear bands and in compaction bands which accommodate the deformation and weaken the ice aggregate. This has major implications for the passage of meltwater in ice sheets and the formation of the layering recognized in glaciers.
Lucas Zeller, Daniel McGrath, Scott W. McCoy, and Jonathan Jacquet
The Cryosphere, 18, 525–541, https://doi.org/10.5194/tc-18-525-2024, https://doi.org/10.5194/tc-18-525-2024, 2024
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In this study we developed methods for automatically identifying supraglacial lakes in multiple satellite imagery sources for eight glaciers in Nepal. We identified a substantial seasonal variability in lake area, which was as large as the variability seen across entire decades. These complex patterns are not captured in existing regional-scale datasets. Our findings show that this seasonal variability must be accounted for in order to interpret long-term changes in debris-covered glaciers.
Laura Melling, Amber Leeson, Malcolm McMillan, Jennifer Maddalena, Jade Bowling, Emily Glen, Louise Sandberg Sørensen, Mai Winstrup, and Rasmus Lørup Arildsen
The Cryosphere, 18, 543–558, https://doi.org/10.5194/tc-18-543-2024, https://doi.org/10.5194/tc-18-543-2024, 2024
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Lakes on glaciers hold large volumes of water which can drain through the ice, influencing estimates of sea level rise. To estimate water volume, we must calculate lake depth. We assessed the accuracy of three satellite-based depth detection methods on a study area in western Greenland and considered the implications for quantifying the volume of water within lakes. We found that the most popular method of detecting depth on the ice sheet scale has higher uncertainty than previously assumed.
Taigang Zhang, Weicai Wang, and Baosheng An
The Cryosphere, 17, 5137–5154, https://doi.org/10.5194/tc-17-5137-2023, https://doi.org/10.5194/tc-17-5137-2023, 2023
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Detailed glacial lake bathymetry surveys are essential for accurate glacial lake outburst flood (GLOF) simulation and risk assessment. We creatively developed a conceptual model for glacial lake bathymetric distribution. The basic idea is that the statistical glacial lake volume–area curves conform to a power-law relationship indicating that the idealized geometric shape of the glacial lake basin should be hemispheres or cones.
Celia Trunz, Kristin Poinar, Lauren C. Andrews, Matthew D. Covington, Jessica Mejia, Jason Gulley, and Victoria Siegel
The Cryosphere, 17, 5075–5094, https://doi.org/10.5194/tc-17-5075-2023, https://doi.org/10.5194/tc-17-5075-2023, 2023
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Models simulating water pressure variations at the bottom of glaciers must use large storage parameters to produce realistic results. Whether that storage occurs englacially (in moulins) or subglacially is a matter of debate. Here, we directly simulate moulin volume to constrain the storage there. We find it is not enough. Instead, subglacial processes, including basal melt and input from upstream moulins, must be responsible for stabilizing these water pressure fluctuations.
Christian Schoof
The Cryosphere, 17, 4797–4815, https://doi.org/10.5194/tc-17-4797-2023, https://doi.org/10.5194/tc-17-4797-2023, 2023
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Computational models that seek to predict the future behaviour of ice sheets and glaciers typically rely on being able to compute the rate at which a glacier slides over its bed. In this paper, I show that the degree to which the glacier bed is
hydraulically connected(how easily water can flow along the glacier bed) plays a central role in determining how fast ice can slide.
Christian Schoof
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.
Nicole Clerx, Horst Machguth, Andrew Tedstone, Nicolas Jullien, Nander Wever, Rolf Weingartner, and Ole Roessler
The Cryosphere, 16, 4379–4401, https://doi.org/10.5194/tc-16-4379-2022, https://doi.org/10.5194/tc-16-4379-2022, 2022
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Meltwater runoff is one of the main contributors to mass loss on the Greenland Ice Sheet that influences global sea level rise. However, it remains unclear where meltwater runs off and what processes cause this. We measured the velocity of meltwater flow through snow on the ice sheet, which ranged from 0.17–12.8 m h−1 for vertical percolation and from 1.3–15.1 m h−1 for lateral flow. This is an important step towards understanding where, when and why meltwater runoff occurs on the ice sheet.
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.
Lauren C. Andrews, Kristin Poinar, and Celia Trunz
The Cryosphere, 16, 2421–2448, https://doi.org/10.5194/tc-16-2421-2022, https://doi.org/10.5194/tc-16-2421-2022, 2022
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We introduce a model for moulin geometry motivated by the wide range of sizes and shapes of explored moulins. Moulins comprise 10–14 % of the Greenland englacial–subglacial hydrologic system and act as time-varying water storage reservoirs. Moulin geometry can vary approximately 10 % daily and over 100 % seasonally. Moulin shape modulates the efficiency of the subglacial system that controls ice flow and should thus be included in hydrologic models.
Rohi Muthyala, Åsa K. Rennermalm, Sasha Z. Leidman, Matthew G. Cooper, Sarah W. Cooley, Laurence C. Smith, and Dirk van As
The Cryosphere, 16, 2245–2263, https://doi.org/10.5194/tc-16-2245-2022, https://doi.org/10.5194/tc-16-2245-2022, 2022
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In situ measurements of meltwater discharge through supraglacial stream networks are rare. The unprecedentedly long record of discharge captures diurnal and seasonal variability. Two major findings are (1) a change in the timing of peak discharge through the melt season that could impact meltwater delivery in the subglacial system and (2) though the primary driver of stream discharge is shortwave radiation, longwave radiation and turbulent heat fluxes play a major role during high-melt episodes.
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.
Colin J. Gleason, Kang Yang, Dongmei Feng, Laurence C. Smith, Kai Liu, Lincoln H. Pitcher, Vena W. Chu, Matthew G. Cooper, Brandon T. Overstreet, Asa K. Rennermalm, and Jonathan C. Ryan
The Cryosphere, 15, 2315–2331, https://doi.org/10.5194/tc-15-2315-2021, https://doi.org/10.5194/tc-15-2315-2021, 2021
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We apply first-principle hydrology models designed for global river routing to route flows hourly through 10 000 individual supraglacial channels in Greenland. Our results uniquely show the role of process controls (network density, hillslope flow, channel friction) on routed meltwater. We also confirm earlier suggestions that large channels do not dewater overnight despite the shutdown of runoff and surface mass balance runoff being mistimed and overproducing runoff, as validated in situ.
Kristin Poinar and Lauren C. Andrews
The Cryosphere, 15, 1455–1483, https://doi.org/10.5194/tc-15-1455-2021, https://doi.org/10.5194/tc-15-1455-2021, 2021
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This study addresses Greenland supraglacial lake drainages. We analyze ice deformation associated with lake drainages over 18 summers to assess whether
precursorstrain-rate events consistently precede lake drainages. We find that currently available remote sensing data products cannot resolve these events, and thus we cannot predict future lake drainages. Thus, future avenues for evaluating this hypothesis will require major field-based GPS or photogrammetry efforts.
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.
Léo Decaux, Mariusz Grabiec, Dariusz Ignatiuk, and Jacek Jania
The Cryosphere, 13, 735–752, https://doi.org/10.5194/tc-13-735-2019, https://doi.org/10.5194/tc-13-735-2019, 2019
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Due to the fast melting of glaciers around the world, it is important to characterize the evolution of the meltwater circulation beneath them as it highly impacts their velocity. By using very
high-resolution satellite images and field measurements, we modelized it for two Svalbard glaciers. We determined that for most of Svalbard glaciers it is crucial to include their surface morphology to obtain a reliable model, which is not currently done. Having good models is key to predicting our future.
Sebastian Beyer, Thomas Kleiner, Vadym Aizinger, Martin Rückamp, and Angelika Humbert
The Cryosphere, 12, 3931–3947, https://doi.org/10.5194/tc-12-3931-2018, https://doi.org/10.5194/tc-12-3931-2018, 2018
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The evolution of subglacial channels below ice sheets is very important for the dynamics of glaciers as the water acts as a lubricant. We present a new numerical model (CUAS) that generalizes existing approaches by accounting for two different flow situations within a single porous medium layer: (1) a confined aquifer if sufficient water supply is available and (2) an unconfined aquifer, otherwise. The model is applied to artificial scenarios as well as to the Northeast Greenland Ice Stream.
Sammie Buzzard, Daniel Feltham, and Daniela Flocco
The Cryosphere, 12, 3565–3575, https://doi.org/10.5194/tc-12-3565-2018, https://doi.org/10.5194/tc-12-3565-2018, 2018
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Surface lakes on ice shelves can not only change the amount of solar energy the ice shelf receives, but may also play a pivotal role in sudden ice shelf collapse such as that of the Larsen B Ice Shelf in 2002.
Here we simulate current and future melting on Larsen C, Antarctica’s most northern ice shelf and one on which lakes have been observed. We find that should future lakes occur closer to the ice shelf front, they may contain sufficient meltwater to contribute to ice shelf instability.
Thomas Lelandais, Édouard Ravier, Stéphane Pochat, Olivier Bourgeois, Christopher Clark, Régis Mourgues, and Pierre Strzerzynski
The Cryosphere, 12, 2759–2772, https://doi.org/10.5194/tc-12-2759-2018, https://doi.org/10.5194/tc-12-2759-2018, 2018
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Scattered observations suggest that subglacial meltwater routes drive ice stream dynamics and ice sheet stability. We use a new experimental approach to reconcile such observations into a coherent story connecting ice stream life cycles with subglacial hydrology and bed erosion. Results demonstrate that subglacial flooding, drainage reorganization, and valley development can control an ice stream lifespan, thus opening new perspectives on subglacial processes controlling ice sheet instabilities.
Camilo Rada and Christian Schoof
The Cryosphere, 12, 2609–2636, https://doi.org/10.5194/tc-12-2609-2018, https://doi.org/10.5194/tc-12-2609-2018, 2018
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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.
Penelope How, Douglas I. Benn, Nicholas R. J. Hulton, Bryn Hubbard, Adrian Luckman, Heïdi Sevestre, Ward J. J. van Pelt, Katrin Lindbäck, Jack Kohler, and Wim Boot
The Cryosphere, 11, 2691–2710, https://doi.org/10.5194/tc-11-2691-2017, https://doi.org/10.5194/tc-11-2691-2017, 2017
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This study provides valuable insight into subglacial hydrology and dynamics at tidewater glaciers, which remains a poorly understood area of glaciology. It is a unique study because of the wealth of information provided by simultaneous observations of glacier hydrology at Kronebreen, a tidewater glacier in Svalbard. All these elements build a strong conceptual picture of the glacier's hydrological regime over the 2014 melt season.
Sasha P. Carter, Helen A. Fricker, and Matthew R. Siegfried
The Cryosphere, 11, 381–405, https://doi.org/10.5194/tc-11-381-2017, https://doi.org/10.5194/tc-11-381-2017, 2017
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We use a new process-scale model for the drainage of active subglacial lakes in Antarctica that considers channel incision into the soft sedimentary bed. Compared to models with ice-incised channels, our model better reproduces magnitudes and recurrence intervals of active subglacial lake fill–drain cycles derived from satellite altimetry observations.
Christine F. Dow, Mauro A. Werder, Sophie Nowicki, and Ryan T. Walker
The Cryosphere, 10, 1381–1393, https://doi.org/10.5194/tc-10-1381-2016, https://doi.org/10.5194/tc-10-1381-2016, 2016
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We examine the development and drainage of subglacial lakes in the Antarctic using a finite element hydrology model. Model outputs show development of slow-moving pressure waves initiated from water funneled from a large catchment into the ice stream. Lake drainage occurs due to downstream channel formation and changing system hydraulic gradients. These model outputs have implications for understanding controls on ice stream dynamics.
Andreas Bech Mikkelsen, Alun Hubbard, Mike MacFerrin, Jason Eric Box, Sam H. Doyle, Andrew Fitzpatrick, Bent Hasholt, Hannah L. Bailey, Katrin Lindbäck, and Rickard Pettersson
The Cryosphere, 10, 1147–1159, https://doi.org/10.5194/tc-10-1147-2016, https://doi.org/10.5194/tc-10-1147-2016, 2016
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
L. Karlstrom, A. Zok, and M. Manga
The Cryosphere, 8, 537–546, https://doi.org/10.5194/tc-8-537-2014, https://doi.org/10.5194/tc-8-537-2014, 2014
B. de Fleurian, O. Gagliardini, T. Zwinger, G. Durand, E. Le Meur, D. Mair, and P. Råback
The Cryosphere, 8, 137–153, https://doi.org/10.5194/tc-8-137-2014, https://doi.org/10.5194/tc-8-137-2014, 2014
S. J. Livingstone, C. D. Clark, J. Woodward, and J. Kingslake
The Cryosphere, 7, 1721–1740, https://doi.org/10.5194/tc-7-1721-2013, https://doi.org/10.5194/tc-7-1721-2013, 2013
J. Oerlemans
The Cryosphere, 7, 1557–1564, https://doi.org/10.5194/tc-7-1557-2013, https://doi.org/10.5194/tc-7-1557-2013, 2013
M. Prasch, W. Mauser, and M. Weber
The Cryosphere, 7, 889–904, https://doi.org/10.5194/tc-7-889-2013, https://doi.org/10.5194/tc-7-889-2013, 2013
W. Tangborn
The Cryosphere, 7, 867–875, https://doi.org/10.5194/tc-7-867-2013, https://doi.org/10.5194/tc-7-867-2013, 2013
S. Gascoin, C. Kinnard, R. Ponce, S. Lhermitte, S. MacDonell, and A. Rabatel
The Cryosphere, 5, 1099–1113, https://doi.org/10.5194/tc-5-1099-2011, https://doi.org/10.5194/tc-5-1099-2011, 2011
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Short summary
We present measurements of ice density that show the melting bare-ice surface of the Greenland ice sheet study site is porous and saturated with meltwater. The data suggest up to 18 cm of meltwater is temporarily stored within porous, low-density ice. The findings imply meltwater drainage off the ice sheet surface is delayed and that the surface mass balance of the ice sheet during summer cannot be estimated solely from ice surface elevation change measurements.
We present measurements of ice density that show the melting bare-ice surface of the Greenland...
