Preprints
Filtering by Subject: Glaciology
Increased crevassing across accelerating Greenland Ice Sheet margins
Published: 2023-09-02
Subjects: Glaciology
The extent of surface crevassing on the Greenland Ice Sheet is a large source of uncertainty in processes controlling mass loss, including iceberg calving, ice rheology, and water routing. However, no work to date has comprehensively mapped the location of surface crevasses or examined their evolution through time. Here, we use high-resolution digital elevation models to map the 3-dimensional [...]
What can radar-based measures of subglacial hydrology tell us about basal shear stress? A case study at Thwaites Glacier, West Antarctica
Published: 2023-08-29
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Ice sheet models use observations to infer basal shear stress, but the variety of methods and datasets available has resulted in a wide range of estimates. Radar-based metrics such as reflectivity and specularity content have been used to characterize subglacial hydrologic conditions that are linked to spatial variations in basal shear stress. We explore whether radar metrics can be used to [...]
Transporting Heat Flux From the US and Europe to Antarctica Guided by Regional Seismic Structure
Published: 2023-07-08
Subjects: Earth Sciences, Geophysics and Seismology, Glaciology, Physical Sciences and Mathematics
Subglacial geothermal heat flux affects the dynamics of the Antarctic ice sheet but is poorly known. We estimate heat flux across West Antarctica and the interior of East Antarctica by transporting heat flux observations from the contiguous US and Europe, based on seismic structure with a lateral resolution of about \qty{100}{km}. We transport with three Machine Learning models across a hierarchy [...]
Improved representation of laminar and turbulent sheet flow in subglacial drainage models
Published: 2023-07-07
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
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 [...]
A framework for estimating the anthropogenic part of Antarctica’s sea level contribution in a synthetic setting
Published: 2023-06-19
Subjects: Earth Sciences, Glaciology, Other Oceanography and Atmospheric Sciences and Meteorology
The relative contributions of anthropogenic climate change and internal variability in sea level rise from the West Antarctic Ice Sheet are yet to be determined. Even the way to address this question is not yet clear, since these two are linked through ice-ocean feedbacks and probed using ice sheet models with substantial uncertainty. Here we demonstrate how their relative contributions can be [...]
Applying Machine Learning to Characterize and Transport the Relationship Between Seismic Structure and Surface Heat Flux
Published: 2023-06-15
Subjects: Geophysics and Seismology, Glaciology
Geothermal heat flux beneath the Greenland and Antarctic ice sheets is an important boundary condition for ice sheet dynamics. Subglacial heat flux is rarely measured directly, so it has been inferred indirectly from proxies (e.g. seismic structure, magnetic Curie depth, surface topography). We seek to improve understanding of the relationship between heat flux and one such proxy---seismic [...]
The role of thermal notch erosion in forcing localised calving failure and short-term increases in velocity at a lake-terminating glacier in southeast Iceland
Published: 2023-05-25
Subjects: Glaciology
We utilised repeat high-resolution UAV-SfM surveys, alongside terrestrial photography acquired in-situ, to investigate, for the first time, the role of thermal notch erosion in forcing localised calving failure and subsequent short-term increases in velocity at a lake-terminating glacier. This data was acquired daily (where possible) across one week in July 2019 and two weeks in July 2021 to [...]
Harmonizing GCW Cryosphere Vocabularies with ENVO and SWEET: Towards a General Model for Semantic Harmonization
Published: 2023-05-17
Subjects: Databases and Information Systems, Geomorphology, Glaciology, Other Earth Sciences
This paper presents the specific process we, as part of the Earth Science Information Partners (ESIP) Semantic Harmonization Cluster, used to harmonize terms from the Global Cryosphere Watch (GCW) compilation of cryospheric terms with the Semantic Web for Earth and Environmental Terminology (SWEET) and the Environment Ontology (ENVO). In addition, we summarize a number of leading practices which [...]
Different mechanisms of Arctic first-year sea-ice ridge consolidation observed during the MOSAiC expedition
Published: 2023-05-10
Subjects: Earth Sciences, Glaciology, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Sea-ice ridges constitute a large fraction of the ice volume in the Arctic Ocean, yet we know little about the evolution of these ice masses. Here we examine the thermal and morphological evolution of an Arctic first-year sea-ice ridge, from its formation to advanced melt. Initially the mean keel depth was 5.6 m and mean sail height was 0.7 m. The initial rubble macroporosity (fraction of [...]
Ice flow model emulator based on physics-informed deep learning
Published: 2023-05-08
Subjects: Glaciology
Convolutional Neural Networks (CNN) trained from high-order ice flow model realizations have proven to be outstanding emulators in terms of fidelity and computational performance. However, the dependence on an ensemble of realizations of an instructor model renders this strategy difficult to generalize to a variety of ice flow regimes found in the nature. To overcome this issue, we adopt the [...]
Linear analysis of ice-shelf topography response to basal melting and freezing
Published: 2023-04-28
Subjects: Applied Mathematics, Dynamic Systems, Earth Sciences, Fluid Dynamics, Glaciology, Physical Sciences and Mathematics, Physics
Floating ice shelves in Antarctica and Greenland limit land-ice contributions to sea level rise by resisting the flow of grounded ice. Melting at the surface and base of ice shelves can lead to destabilisation by promoting thinning and fracturing. Basal melting often results in channelised features that manifest as surface topography due to buoyancy. The assumption of hydrostatic flotation [...]
Assessing multi-hazard susceptibility to cryospheric hazards: lesson learnt from an Alaskan example
Published: 2023-04-28
Subjects: Applied Statistics, Geomorphology, Glaciology, Statistical Models
Classifying a given landscape on the basis of its susceptibility to surface processes is a standard procedure in low to mid-latitudes. Conversely, these procedures have hardly been explored in periglacial regions, primarily because of the limited presence of human settlements and, therefore, the little need for risk assessment. However, global warming is radically changing this situation and [...]
Reconstructing subglacial lake activity with an altimetry-based inverse method
Published: 2023-04-28
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Subglacial lake water-volume changes produce ice-elevation anomalies that provide clues about water flow beneath glaciers and ice sheets. Significant challenges remain in the quantitative interpretation of these elevation-change anomalies because the surface expression of subglacial lake activity depends on basal conditions, rate of water-volume change, and ice rheology. To address these [...]
A shallow approximation for ice streams sliding over strong beds
Published: 2023-03-29
Subjects: Glaciology, Partial Differential Equations
Ice streams are regions of rapid ice sheet flow characterised by a high degree of sliding over a deforming bed. The Shallow Shelf Approximation (SSA) provides a convenient way to obtain closed-form approximations of the velocity and flux in a rapidly-sliding ice stream when the basal drag is much less than the driving stress. However, the validity of the SSA approximation breaks down when the [...]
Glacier projections sensitivity to temperature-index model choices and calibration strategies
Published: 2023-03-03
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Glacier models contribute significantly to the uncertainty of glacier change projections. In this study, we focus on temperature-index mass-balance (MB) models and their calibration, exploring the impact of various design choices on projections. Using the Open Global Glacier Model (OGGM), we compare the effects of different surface-type dependent degree-day factors, temporal climate resolutions [...]