Article
Geosciences, Multidisciplinary
K. A. Hogan, N. S. Arnold, R. D. Larter, J. D. Kirkham, R. Noormets, C. O. Cofaigh, N. R. Golledge, J. A. Dowdeswell
Summary: The subglacial hydrological system plays a crucial role in the behavior of ice sheets, but is difficult to observe. This study combines investigations and modeling to reveal the accumulation, routing, and erosion potential of subglacial water over long timescales. The findings support previous theories and present a viable pattern for subglacial drainage.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2022)
Article
Geosciences, Multidisciplinary
Wolfgang Rack, Daniel Price, Christian Haas, Patricia J. Langhorne, Greg H. Leonard
Summary: Airborne measurements and satellite image analysis reveal regional variability in sea ice thickness distribution in the western Ross Sea, Antarctica, with heavily deformed ice concentrated in ridges with thicknesses of 3.0-11.8 m. About 80% of the ice is heavily deformed, suggesting that sea ice is thicker than in the central Ross Sea.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Geology
Wlodzimierz Narloch, Tomasz Werner, Karol Tylmann
Summary: This study investigates subglacial sediment deformation under a Pleistocene fast-flowing ice sheet by combining micro- and macroscale studies and quantitative analyses in a complex sedimentary succession. The main finding is that AMS reveals shear strain development and ice flow direction in structurally and texturally complex deposits under weak coupling conditions at the ice-bed interface beneath a fast-flowing/streaming ice sheet.
SEDIMENTARY GEOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Benjamin H. Hills, Knut Christianson, Andrew O. Hoffman, T. J. Fudge, Nicholas Holschuh, Emma C. Kahle, Howard Conway, John E. Christian, Annika N. Horlings, Gemma K. O'Connor, Eric J. Steig
Summary: Geophysical exploration of a subglacial lake near the South Pole suggests that it has been thermodynamically stable for at least the last 120,000 years, making it a promising site for sediment coring.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Oceanography
P. J. Langhorne, C. Haas, D. Price, W. Rack, G. H. Leonard, G. M. Brett, S. Urbini
Summary: This study presents the first inventory of fast ice thickness close to its annual maximum, using a 700 km airborne electromagnetic survey. The results show that rough ice occupies a significant portion and has larger thickness, while the sub-ice platelet layers (SIPLs) are thin in some areas but still have important implications.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Article
Multidisciplinary Sciences
Nathan Maier, Florent Gimbert, Fabien Gillet-Chaulet
Summary: Basal motion plays a crucial role in ice speeds in Greenland, which is influenced by meltwater delivery to the ice base. Increasing melt rates enhance bed friction and cause the ice to slow down. However, factors besides melt rates primarily control the impact of melt forcing. The weakening of the southern ablation zone and the strengthening of the northern ablation zone suggest that dynamic changes leading to increased mass loss are likely to occur in northern Greenland as temperatures increase.
Article
Oceanography
Daniel N. Goldberg, Andrew G. Twelves, Paul R. Holland, Martin G. Wearing
Summary: Little is known about Antarctic subglacial hydrology, but it is believed that subglacial runoff enhances submarine melt locally through buoyancy effects. This study examines the effects of runoff on sea ice and oceanography on the Continental Shelf, and finds that runoff enhances localized melt and reduces summer sea ice volume. Runoff-driven melt and circulation may be an important missing process in regional Antarctic ocean models.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Article
Geosciences, Multidisciplinary
Guogang Li, Ruyuan Bu, Liang Yi, Bangqi Hu, Yunhai Li, Youjun Ji, Yixin Li, Liang Wang
Summary: This study focuses on the paleoceanographic research in the Ross Sea region of Antarctica. By analyzing a sediment sample, the sedimentation rate based on Th-230 isotopes is determined, and a large amount of ice-rafted debris is found in the sediments, suggesting an enhancement of these features in a warm climate. Additionally, this study observes the dominant role of biogenic processes in the ice sheet changes and establishes the correlation between regional paleoenvironmental processes and the temperature of the East Antarctic ice sheet.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Geography, Physical
Alexander A. Robel, Samuel S. Pegler, Ginny Catania, Denis Felikson, Lauren M. Simkins
Summary: Observations show that some glaciers remain at peaks in bed topography despite significant changes in climate, but can undergo sudden retreat after several years or decades. Model simulations suggest that the persistence of a glacier at a bed peak is due to slowing ice flow as it moves up a reverse-sloping bed. It is difficult to determine the future behavior of glaciers solely based on current observations.
JOURNAL OF GLACIOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Calvin Shackleton, Kenichi Matsuoka, Geir Moholdt, Brice Van Liefferinge, John Paden
Summary: The topographic variability beneath ice sheets plays a crucial role in regulating ice flow, basal melting, refreezing processes, and meltwater drainage. A study conducted in Dome Fuji, inland East Antarctica, reveals that the landscape variability beneath the ice sheet could have a significant impact on the distribution and rates of basal melting. It also emphasizes the importance of considering topographic uncertainty when planning future surveys to map the landscape beneath thick ice in this region and elsewhere in Antarctica and Greenland.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2023)
Article
Geosciences, Multidisciplinary
Xi Lu, Liming Jiang, Cunde Xiao, Daan Li
Summary: This study investigates the spatial and temporal characteristics of ice motion in the Northeast Greenland Ice Stream (NEGIS) and finds that subglacial topography and surface runoff play crucial roles in ice motion.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Multidisciplinary Sciences
Christian Helanow, Neal R. Iverson, Jacob B. Woodard, Lucas K. Zoet
Summary: In this study, a process-based, three-dimensional model of glacier slip was applied to measured bed topographies, showing that considering actual glacier beds can eliminate or make rate-weakening drag insignificant, thereby unifying process-based models of slip with certain ice-sheet model parameterizations. The computed slip laws have the same form as those observed in experiments with ice dragged over deformable till, possibly pointing to a universal slip law that could simplify and improve estimations of glacier discharges to the oceans.
Article
Geography, Physical
Sarah U. Neuhaus, Slawek M. Tulaczyk, Nathan D. Stansell, Jason J. Coenen, Reed P. Scherer, Jill A. Mikucki, Ross D. Powell
Summary: Understanding past ice sheet configurations is important for predicting future ice sheet dynamics and calibrating models. In the Ross Sea sector of Antarctica, recent research suggests that the grounding line of the West Antarctic Ice Sheet retreated and readvanced in response to changes in climate, contrary to previous hypotheses that attributed the motion to ice sheet dynamics and glacioisostatic rebound.
Article
Geosciences, Multidisciplinary
David E. Gwyther, Christine F. Dow, Stefan Jendersie, Noel Gourmelen, Benjamin K. Galton-Fenzi
Summary: Subglacial freshwater discharge from beneath Antarctic glaciers has a significant impact on ice shelf basal melting. The difficulty in directly observing this process highlights the importance of modeling. By injecting subglacial discharge into an ocean model, we show that it increases melting in the outflow region, driven by the formation of a buoyant plume rather than heat addition, and has far-reaching effects. Subglacial hydrology-induced basal melting is crucial for ice shelf stability but often overlooked in ice-ocean models.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Meteorology & Atmospheric Sciences
Usama Farooq, Wolfgang Rack, Adrian McDonald, Stephen Howell
Summary: This study explores the interaction between the atmosphere and sea ice in the Western Ross Sea using high-resolution sea ice drift data and surface wind model output. The results show a heterogeneous pattern of sea ice movement in different areas, with the directional constancy of sea ice drift closely related to the wind fields. The study also identifies localized wind-driven sea ice drift as the primary factor in this coastal area.
Article
Geography, Physical
Michael R. Prior-Jones, Elizabeth A. Bagshaw, Jonathan Lees, Lindsay Clare, Stephen Burrow, Mauro A. Werder, Nanna B. Karlsson, Dorthe Dahl-Jensen, Thomas R. Chudley, Poul Christoffersen, Jemma L. Wadham, Samuel H. Doyle, Bryn Hubbard
Summary: Cryoegg is a spherical probe that can be deployed into subglacial hydrological systems to measure temperature, pressure, and electrical conductivity and return data wirelessly. It has demonstrated utility in englacial channels and moulins, with significant data transmission performance in cold ice.
JOURNAL OF GLACIOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Samuel J. Cook, Poul Christoffersen, Martin Truffer, Thomas R. Chudley, Antonio Abellan
Summary: The study reveals significant variations in calving activity over time that cannot be simply described by mathematical relationships. There is a statistically significant relationship between surface melt and the number of calving events, but no direct correlation between surface melt and the volume of these events. Additionally, calving losses appear to have no clear single control factor.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2021)
Article
Multidisciplinary Sciences
Robert Law, Poul Christoffersen, Bryn Hubbard, Samuel H. Doyle, Thomas R. Chudley, Charlotte M. Schoonman, Marion Bougamont, Bas des Tombe, Bart Schilperoort, Cedric Kechavarzi, Adam Booth, Tun Jan Young
Summary: Measurements of ice temperature are crucial for understanding ice viscosity and thermodynamic processes within glaciers. Researchers advanced their understanding of glacier thermodynamics by obtaining a high-vertical-resolution temperature-sensing profile from a deep borehole in Greenland. The findings reveal notable spatial heterogeneity in conditions facilitating the fast motion of marine-terminating glaciers in Greenland, both vertically and at the catchment scale.
Article
Geosciences, Multidisciplinary
S. T. Peters, D. M. Schroeder, W. Chu, D. Castelletti, M. S. Haynes, P. Christoffersen, A. Romero-Wolf
Summary: The study found that passive radio sounding can accurately measure ice thickness, providing a new method for monitoring ice sheets. Passive radar sounding could provide low-resource time-series measurements of the cryosphere, enabling observation and understanding of evolving englacial and subglacial conditions across Greenland and Antarctica with unprecedented coverage and resolution.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Geosciences, Multidisciplinary
T. R. Chudley, P. Christoffersen, S. H. Doyle, T. P. F. Dowling, R. Law, C. M. Schoonman, M. Bougamont, B. Hubbard
Summary: This study reveals that crevasse ponding on the Greenland Ice Sheet is influenced by surface stress and does not follow the same controls as supraglacial lakes and crevasses. The preferential location of ponded crevasses in regions of compressive surface-parallel mean stress indicates a spatially heterogeneous transfer of meltwater, impacting processes such as subglacial drainage and ice heating.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2021)
Article
Geochemistry & Geophysics
Nicole L. Bienert, Dustin M. Schroeder, Sean T. Peters, Emma J. MacKie, Eliza J. Dawson, Matthew R. Siegfried, Rohan Sanda, Poul Christoffersen
Summary: This study presents a postprocessing synchronization technique that eliminates the hardware complexity of real-time synchronization, enabling coherent bistatic radar to recover basal echoes at long offsets. Experimental results show that basal echoes can be measured at angles beyond the point of total internal reflection (TIR), challenging the previous literature's assumption of a hard physical limit.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Geography, Physical
Samuel J. Cook, Poul Christoffersen, Joe Todd
Summary: A fully coupled 3D full-Stokes model was applied to simulate Store Glacier in west Greenland, revealing differences in subglacial hydrology between high melt year 2012 and low melt year 2017. Hydrodynamic feedbacks were found to have significant impacts on channel growth and calving at the glacier terminus.
JOURNAL OF GLACIOLOGY
(2022)
Article
Geography, Physical
Samuel H. Doyle, Bryn Hubbard, Poul Christoffersen, Robert Law, Duncan R. Hewitt, Jerome A. Neufeld, Charlotte M. Schoonman, Thomas R. Chudley, Marion Bougamont
Summary: This study reports detailed measurements of subglacial water pressure response to drilling and connecting adjacent water-filled boreholes through kilometre-thick ice in Greenland. The measurements provide evidence for gap opening at the ice-sediment interface and stress transfer affecting water pressure in hydraulically-isolated cavities. The study suggests that opening gaps at the ice-sediment interface and subsequent changes in hydraulic conductivity deserve further attention.
JOURNAL OF GLACIOLOGY
(2022)
Article
Multidisciplinary Sciences
Tun Jan Young, Poul Christoffersen, Marion Bougamont, Slawek M. Tulaczyk, Bryn Hubbard, Kenneth D. Mankoff, Keith W. Nicholls, Craig L. Stewart
Summary: Subglacial hydrologic systems play a key role in regulating ice sheet flow. This study reveals the presence of basal melt and unexpectedly warm subglacial conditions beneath a large Greenlandic outlet glacier. These findings have implications for understanding and modeling ice sheet behavior.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Geography, Physical
Samuel J. Cook, Poul Christoffersen, Iain Wheel
Summary: Tidewater glaciers are complex and challenging to study due to their nature and inaccessible environments. Modelling is a possible solution, but the complexities require computationally expensive methods. Lack of data for validation is another obstacle. However, progress is being made in modelling these glaciers to include all relevant processes. The key challenges remaining are more realistic representations of calving and coupling glacier modelling with fjord circulation modelling.
ANNALS OF GLACIOLOGY
(2023)
Article
Geography, Physical
Adam D. D. Booth, Poul Christoffersen, Andrew Pretorius, Joseph Chapman, Bryn Hubbard, Emma C. C. Smith, Sjoerd de Ridder, Andy Nowacki, Bradley Paul Lipovsky, Marine Denolle
Summary: Distributed Acoustic Sensing (DAS) is a valuable tool for glaciological seismic applications, but analyzing the large data volumes generated poses computational challenges. Active-source DAS has the potential to image and characterize subglacial sediment, but the lack of subglacial velocity constraint limits accuracy. Compression using the frequency-wavenumber (f-k) transform and a convolutional neural network provides a significant improvement in efficiency for analyzing cryoseismic events. Combining active and passive-source data with machine learning frameworks unlocks the potential of large DAS datasets for future applications.
ANNALS OF GLACIOLOGY
(2023)
Article
Multidisciplinary Sciences
Robert Law, Poul Christoffersen, Emma MacKie, Samuel Cook, Marianne Haseloff, Olivier Gagliardini
Summary: Uncertainty associated with ice sheet motion affects sea level rise predictions. Imperfect representations of physical processes in ice sheet models, such as basal slip and internal ice deformation, contribute to this uncertainty. In this study, three-dimensional domains from fast-moving and slow-moving ice sheet settings in Greenland were modeled, and the results showed the formation of a spatially highly variable layer of temperate ice in both settings. The ice motion patterns observed diverged significantly from those predicted using smooth topography. Developing parameterizations of this complex motion can enhance the realism of ice sheet models.
Proceedings Paper
Geosciences, Multidisciplinary
Akua A. McLeod, Sean T. Peters, Riley Culberg, Dustin M. Schroeder, Nicole L. Bienert, Winnie Chu, Tun Jan Young, Poul Christoffersen
Summary: The paper analyzes a two-year dataset collected by a Multi-Input Multi-Output Autonomous Phase-Sensitive Radio-Echo Sounder (MIMO ApRES) at Store Glacier in West Greenland, documenting the formation of a crevasse under the instrument. The study presents methods for processing the data and removing artifacts, and shows that the bottom of a crevasse can be detected in the processed images.
2022 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS 2022)
(2022)
Article
Geography, Physical
Tun Jan Young, Carlos Martin, Poul Christoffersen, Dustin M. Schroeder, Slawek M. Tulaczyk, Eliza J. Dawson
Summary: The study utilizes coherent ice-penetrating radar to investigate the crystal orientation fabric near the Western Antarctic Ice Sheet (WAIS) Divide ice core site, revealing a close relationship between fabric asymmetry and modern surface strain direction at depths of at least 1400 meters. The results suggest that the deformation regime at WAIS Divide has remained relatively consistent through the majority of the Holocene.
Article
Geosciences, Multidisciplinary
Bryn Hubbard, Poul Christoffersen, Samuel H. Doyle, Thomas R. Chudley, Charlotte M. Schoonman, Robert Law, Marion Bougamont
Summary: The optical televiewer borehole logging in a crevassed region of Store Glacier, Greenland, revealed high-angle planes of refrozen ice layers that are likely traces of former open crevasses. These crevasse traces decrease in frequency with depth and show a consistent orientation with a dip of 63 degrees and a strike offset by 71 degrees. These traces represent planes of weakness that may have originated upglacier and are likely to survive surface ablation to reach the glacier terminus.