Preprints
Filtering by Subject: Glaciology
Concepts and capabilities of the Instructed Glacier Model
Published: 2024-04-05
Subjects: Glaciology
We present the concept and capabilities of IGM (https://github.com/jouvetg/igm), a Python-based modeling tool designed for efficiently simulating glacier evolution across various scales. IGM integrates ice thermomechanics, climate-driven surface mass balance, mass conservation, and other processes. Within IGM, the update of all physical model components involves a series of mathematical [...]
DAS to Discharge: Using Distributed Acoustic Sensing (DAS) to infer glacier runoff
Published: 2024-02-08
Subjects: Earth Sciences, Geophysics and Seismology, Glaciology, Physical Sciences and Mathematics
Observations of glacier melt and runoff are of fundamental interest in the study of glaciers and their interactions with their environment. Considerable recent interest has developed around distributed acoustic sensing (DAS), a sensing technique which utilizes Rayleigh backscatter in fiber optic cables to measure the seismo-acoustic wavefield in high spatial and temporal resolution. Here, we [...]
Characteristics of dynamic thickness change across diverse outlet glacier geometries and basal conditions
Published: 2024-01-30
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Outlet glaciers in Greenland are undergoing retreat and diffusive thinning in response to external forcings, but the rates and magnitudes of these responses differ from glacier to glacier for unclear reasons. We test how changes in ice overburden pressure and basal lubrication affect diffusive thinning rates and their spatial patterns by conducting numerical experiments over various idealized [...]
Subtemperate regelation exhibits power-law premelting
Published: 2024-01-13
Subjects: Fluid Dynamics, Glaciology, Other Physics
Wire regelation is a common tabletop demonstration of the pressure-dependence of the ice melting temperature where loaded wires move from top to bottom through a block of ice, yet leaves the block intact. With the background temperature fixed at the bulk melting point $\sim0\,^{\circ}$C, the elevated ice and liquid pressures beneath the wire cause melting because of the negative Clapeyron slope, [...]
Metrological approach for permafrost temperature measurements
Published: 2024-01-12
Subjects: Climate, Environmental Monitoring, Glaciology
Permafrost degradation is a growing direct impact of climate change. Detecting permafrost reductions, in terms of its extension, deepening of the active layer and rise of the base is fundamental to capture the magnitude of trends and address actions and warnings. Temperature profiles in permafrost allow direct understanding of the status of the frozen ground layer and its evolution in time. The [...]
Evidence that seismic anisotropy captures upstream palaeo ice fabric: Implications on present day deformation at Whillans Ice Stream, Antarctica
Published: 2023-11-16
Subjects: Earth Sciences, Geophysics and Seismology, Glaciology, Physical Sciences and Mathematics
Understanding deformation and slip at ice streams, which are responsible for 90% of Antarctic ice loss, is vital for accurately modelling large-scale ice flow. Ice crystal orientation fabric (COF) has a first-order effect on ice stream deformation. For the first time, we use shear-wave splitting (SWS) measurements of basal icequakes at Whillans Ice Stream (WIS), Antarctica, to determine a [...]
Pygoda: a graphical interface to efficiently visualise and explore large sets of geolocated time series
Published: 2023-10-24
Subjects: Categorical Data Analysis, Climate, Computer Sciences, Databases and Information Systems, Earth Sciences, Environmental Monitoring, Environmental Sciences, Environmental Studies, Fresh Water Studies, Geographic Information Sciences, Geophysics and Seismology, Glaciology, Graphics and Human Computer Interfaces, Hydrology, Longitudinal Data Analysis and Time Series, Meteorology, Other Earth Sciences, Other Statistics and Probability, Spatial Science
Modern-day data sets in geosciences may comprise hundreds or thousands of geolocated time series. Despite all the automated tools and new algorithms now available to process and prepare those data before using them in research projects, it can be useful or even necessary to visualise and investigate them manually. Whether it be for data quality assessment, for the preparation of a training data [...]
Future (2015-2100) Antarctic-wide ice-shelf firn air depletion from a statistical firn emulator
Published: 2023-10-13
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Antarctic firn is critical for ice-shelf stability because it stores meltwater that would otherwise pond on the surface. Ponded meltwater increases the risk of hydrofracture, and subsequent potential ice-shelf collapse. Here, we use output from a firn model to build a computationally simpler emulator that uses a random forest to predict ice-shelf firn air content (FAC) based on climate [...]
Modelling lateral meltwater flow and superimposed ice formation atop Greenland's near-surface ice slabs
Published: 2023-10-02
Subjects: Glaciology, Hydrology
At high elevations on the Greenland ice sheet meltwater percolates and refreezes in place, and hence does not contribute to mass loss. However, meltwater generation and associated surface runoff is occurring from increasingly higher altitudes, causing changes in firn stratigraphy that have led to the presence of near-surface ice slabs. These ice slabs force meltwater to flow laterally instead of [...]
Increased crevassing across accelerating Greenland Ice Sheet margins
Published: 2023-09-02
Subjects: Glaciology
Surface crevassing on the Greenland Ice Sheet is a large source of uncertainty in processes controlling mass loss, including calving, ice rheology, and water routing. However, no work 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 volume of crevasse fields across [...]
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 [...]