Preprints
Filtering by Subject: Glaciology
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 [...]
A method for the measurement of seismic attenuation in polar firn
Published: 2023-03-03
Subjects: Geophysics and Seismology, Glaciology
We present seismic measurements of the firn column at Korff Ice Rise, West Antarctica, including measurements of compressional- and shear-wave velocity and attenuation. We describe a modified spectral-ratio method of measuring the seismic quality factor (Q) based on analysis of diving waves, which enables us to characterise the attenuative structure of firn in greater detail than has previously [...]
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 [...]
Detection and Characterization of Discontinuous Motion on Thompson Glacier, Canadian High Arctic, Using Synthetic Aperture Radar Speckle Tracking and Ice-Flow Modeling
Published: 2023-02-23
Subjects: Glaciology
We investigate unusual discontinuous glacier motion on Thompson Glacier, Umingmat Nunaat, Arctic Canada, using synthetic aperture radar (SAR) images and ice-flow modeling. A novel intensity-rescaling scheme is developed to reduce errors in high resolution speckle tracking, resulting in a ~25% improvement in accuracy. Interferometric SAR (InSAR) and speckle tracking using high resolution [...]
Simulating the processes controlling ice-shelf rift paths using damage mechanics
Published: 2023-02-21
Subjects: Glaciology
Rifts are full-thickness fractures that propagate laterally across the ice shelf. They cause ice-shelf weakening and calving of tabular icebergs, and control the initial size of calved icebergs. Here, we present a combined inverse and forward computational modeling framework to capture rifting by combining the vertically integrated momentum balance and anisotropic continuum damage mechanics [...]
Temporal evolution of under-ice meltwater layers and false bottoms and their impact on summer Arctic sea ice mass balance
Published: 2023-02-16
Subjects: Earth Sciences, Glaciology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Low-salinity meltwater from Arctic sea ice and its snow cover accumulates and creates under-ice meltwater layers below sea ice. These meltwater layers can result in the formation of new ice layers, or false bottoms, at the interface of this low-salinity meltwater and colder seawater. As part of the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC), we used a [...]
Evolution of the seasonal dynamics of the lake-terminating glacier Fjallsjökull, southeast Iceland, inferred using high-resolution repeat UAV imagery
Published: 2022-12-16
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Proglacial lakes are becoming ubiquitous at the termini of many glaciers worldwide, leading to increased glacier mass loss and terminus retreat, yet an understanding of the key processes forcing their behaviour is lacking. This study utilised high-resolution repeat uncrewed aerial vehicle (UAV)-Structure from Motion (SfM) imagery to provide insights into the changing dynamics of Fjallsjökull, a [...]
An interconnected palaeo-subglacial lake system in the central Barents Sea
Published: 2022-12-03
Subjects: Earth Sciences, Geology, Geomorphology, Glaciology, Sedimentology
Drainage of meltwater beneath an ice sheet influences ice-flow dynamics. To better predict ice sheet behaviour, it is crucial to understand subglacial hydrological processes. Subglacial lakes are important components of the subglacial hydrological system, with many observed and predicted at the beds of contemporary and palaeo-ice sheets. The technical and logistical challenges of studying [...]
The highly nonlinear viscosity of fast-flowing glacier ice
Published: 2022-12-01
Subjects: Glaciology
Glacier flow modulates sea level and is governed by the viscous deformation of ice. Multiple molecular-scale mechanisms facilitate viscous deformation, but it remains unclear how each contributes to glacier-scale deformation and how to represent them in ice-flow models. Here, we present a model of ice deformation that unifies existing estimates of the viscous parameters and provides a framework [...]
The effect of uncertainties in creep activation energies on modeling ice flow and deformation
Published: 2022-11-21
Subjects: Earth Sciences, Geophysics and Seismology, Glaciology, Physical Sciences and Mathematics
Ice deformation is commonly represented by a power-law constitutive relation, Glen's Flow Law, where deformation (strain) rate equals stress raised to the power n and multiplied by a flow-rate parameter A. Glen's Law represents bulk ice rheology as a single power-law even though multiple mechanisms, each with their own power-law relation and parametric values, act together during viscous [...]
Epitomic Data for Community Land Model Standalone Simulations for Prognostic Analyses of Tropical Mountain Glaciation and Lake Temperature in Pre-Industrial, Last Glacial Maximum, and Extreme Glacial Climates
Published: 2022-11-15
Subjects: Climate, Fresh Water Studies, Glaciology, Hydrology
Global climate models typically simulate climate at much larger spatial scales than tropical mountain glaciers and many of the world’s lakes. Yet some of the proxy data that can be used to validate models of past climate on land come from and are related to these geographic features. Validating global climate models using these proxies requires some method of downscaling global climate model [...]