Andreas Bauder

Last Name

Bauder

First Name

Andreas

ORCID

0000-0001-7197-7706

Organisational unit

09599 - Farinotti, Daniel / Farinotti, Daniel

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Publications 1 - 10 of 75

Mapping the age of ice of Gauligletscher combining surface radionuclide contamination and ice flow modeling
Jouvet, Guillaume; Röllin, Stefan; Sahli, Hans; et al. (2020)
The Cryosphere
In the 1950s and 1960s, specific radionuclides were released into the atmosphere as a result of nuclear weapons testing. This radioactive fallout left its signature on the accumulated layers of glaciers worldwide, thus providing a tracer for ice particles traveling within the gravitational ice flow and being released into the ablation zone. For surface ice dating purposes, we analyze here the activity of 239Pu, 240Pu and 236U radionuclides derived from more than 200 ice samples collected along five flowlines at the surface of Gauligletscher, Switzerland. It was found that contaminations appear band-wise along most of the sampled lines, revealing a V-shaped profile consistent with the ice flow field already observed. Similarities to activities found in ice cores permit the isochronal lines at the glacier from 1960 and 1963 to be identified. Hence this information is used to fine-tune an ice flow/mass balance model, and to accurately map the age of the entire glacier ice. Our results indicate the strong potential for combining radionuclide contamination and ice flow modeling in two different ways. First, such tracers provide unique information on the long-term ice motion of the entire glacier (and not only at its surface), and on the long-term mass balance, and therefore offer an extremely valuable data tool for calibrating ice flows within a model. Second, the dating of surface ice is highly relevant when conducting “horizontal ice core sampling”, i.e., when taking chronological samples of surface ice from the distant past, without having to perform expensive and logistically complex deep ice-core drilling. In conclusion, our results show that an airplane which crash-landed on the Gauligletscher in 1946 will likely soon be released from the ice close to the place where pieces have emerged in recent years, thus permitting the prognosis given in an earlier model to be revised considerably.
AIRETH 2.0 – a revamped helicopter-borne GPR for glaciological applications
Farinotti, Daniel; Moser, Raphael; Anhorn, Barthelemy; et al. (2024)
EGUsphere
Seasonal evolution of an englacial conduit network on a temperate alpine glacier using ground-penetrating radar
Church, Gregory James; Grab, Melchior; Schmelzbach, Cédric; et al. (2019)
AGU Fall Meeting Abstracts
Changes in Ice-Flow Velocity and Surface Elevation from 1874 to 2006 in Rhonegletscher, Switzerland
Nishimura, Daisuke; Sugiyama, Shin; Bauder, Andreas; et al. (2013)
Arctic, Antarctic, and Alpine Research
We have studied changes in the ice-flow velocity and ice thickness in Rhonegletscher, Switzerland, over the period 1874–2006. The flow velocity field and surface elevation were analyzed in the lower half of the glacier using aerial photograph pairs taken in 1970/ 1971, 1981/1982, 1999/2000, and 2005/2006. We also digitized velocities measured by Mercanton (1916) in 1874–1910 by tracking stones distributed on the glacier. The results showed that the ice-flow velocity and ice straining conditions were strongly influenced by changes in the glacier geometry over the last 100 years. For example, the longitudinal strain rate near the current terminus has changed from tensile to compressive since the retreat of the glacier over a steep bedrock slope to a relatively flat region. The velocity decreased over the studied region from 1981 to 2006, which is in agreement with the ice thinning during the same period. However, the rate of the velocity change was smaller in the post-1990 period, because the effect of the thinning on ice flow speed was partly canceled out by the effect of steepening of the ice surface. The velocity change also implied that the magnitude of basal ice motion was influenced by changing subglacial drainage conditions and proglacial lake formation. Our unique data set contributes to a better understanding of ice dynamics under changing glacier geometry. © 2013 Regents of the University of Colorado.
Evolution of Rhonegletscher, Switzerland, over the past 125 years and in the future: application of an improved flowline model
Sugiyama, Shin; Bauder, Andreas; Zahno, Conradin; et al. (2007)
Annals of Glaciology ~ Papers from the International Symposium on Cryospheric Indicators of Global Climate Change: held in Cambridge, UK, on 21-25 August, 2006
To study the past and future evolution of Rhonegletscher, Switzerland, a flowline model was developed to include valley shape effects more accurately than conventional flowband models. In the model, the ice flux at a gridpoint was computed by a two-dimensional ice-flow model applied to the valley cross-section. The results suggested the underestimation of the accumulation area, which seems to be a general problem of flowline modelling arising from the model’s one-dimensional nature. The corrected mass balance was coupled with the equilibrium-line altitude (ELA) change, which was reconstructed for the period 1878–2003 from temperature and precipitation records, to run the model for the past 125 years. The model satisfactorily reproduced both changes in the terminus position and the total ice volume derived from digital elevation models of the surface obtained by analyses of old maps and aerial photographs. This showed the model’s potential to simulate glacier evolution when an accurate mass balance could be determined. The future evolution of Rhonegletscher was evaluated with three mass-balance conditions: the mean for the period 1994–2003, and the most negative (2003) and positive (1978) mass-balance values for the past 50 years. The model predicted volume changes of –18%, –58% and +38% after 50 years for the three conditions, respectively.
Monitoring the seasonal changes of an englacial conduit network using repeated ground-penetrating radar measurements
Church, Gregory James; Grab, Melchior; Schmelzbach, Cédric; et al. (2020)
The Cryosphere
Englacial conduits act as water pathways to feed surface meltwater into the subglacial drainage system. A change of meltwater into the subglacial drainage system can alter the glacier's dynamics. Between 2012 and 2019, repeated 25 MHz ground-penetrating radar (GPR) surveys were carried out over an active englacial conduit network within the ablation area of the temperate Rhonegletscher, Switzerland. In 2012, 2016, and 2017 GPR measurements were carried out only once a year, and an englacial conduit was detected in 2017. In 2018 and 2019 the repetition survey rate was increased to monitor seasonal variations in the detected englacial conduit. The resulting GPR data were processed using an impedance inversion workflow to compute GPR reflection coefficients and layer impedances, which are indicative of the conduit's infill material. The spatial and temporal evolution of the reflection coefficients also provided insights into the morphology of the Rhonegletscher's englacial conduit network. During the summer melt seasons, we observed an active, water-filled, sediment-transporting englacial conduit network that yielded large negative GPR reflection coefficients (<−0.2). The GPR surveys conducted during the summer provided evidence that the englacial conduit was 15–20 m±6 m wide, ∼0.4m±0.35m thick, ∼250m±6m long with a shallow inclination (2∘), and having a sinusoidal shape from the GPR data. We speculate that extensional hydraulic fracturing is responsible for the formation of the conduit as a result of the conduit network geometry observed and from borehole observations. Synthetic GPR waveform modelling using a thin water-filled conduit showed that a conduit thickness larger than 0.4 m (0.3× minimum wavelength) thick can be correctly identified using 25 MHz GPR data. During the winter periods, the englacial conduit no longer transports water and either physically closed or became very thin (<0.1 m), thereby producing small negative reflection coefficients that are caused by either sediments lying within the closed conduit or water within the very thin conduit. Furthermore, the englacial conduit reactivated during the following melt season at an identical position as in the previous year.
20th-century climate change inferred from four long-term point observations of seasonal mass balance
Huss, Matthias; Bauder, Andreas (2009)
Annals of Glaciology
Numerical modeling investigations of the subglacial conditions of the southern Laurentide ice sheet
Bauder, Andreas; Mickelson, David M.; Marshall, Shawn J. (2005)
Annals of Glaciology ~ Papers from the International Symposium on Ice and Water Interactions: processes across the phase boundary: Held in Portland, Oregon, USA, 26-30 July 2004
Sub- and proglacial bed conditions influence advance and retreat of an ice sheet. The existence and distribution of frozen ground is of major importance for better understanding of ice-flow dynamics and landform formation. The southern margin of the Laurentide ice sheet (LIS) was dominated by the presence of relatively thin ice lobes that seem to have been very sensitive to external and internal physical conditions. Their extent and dynamics were highly influenced by the interaction of subglacial and proglacial conditions. A three-dimensional thermomechanical ice-sheet model was coupled with a model for the thermal regime in the upper Earth crust. The model has been applied to the LIS in order to investigate the spatial distribution of thermal conditions at the bed. The evolution of the whole LIS was modeled for the last glacial cycle, with primary attention on correct reconstruction of the southern margin. Our results show extensive temporal and spatial frozen ground conditions. Only a slow degradation of permafrost under the ice was found. We conclude that there are significant interactions between the ice sheet and the underlying frozen ground and that these influence both ice dynamics and landform development.
Changes in geometry and subglacial drainage derived from digital elevation models: Unteraargletscher, Switzerland, 1927-97
Fischer, Urs H.; Braun, André; Bauder, Andreas; et al. (2005)
Annals of Glaciology ~ Papers from the International Symposium on Ice and Water Interactions: Processes across the Phase Boundary: held in Portland, Oregon, USA, 26-30 July 2004
Digital elevation models of the bed and surface of Unteraargletscher, Switzerland, are used to reconstruct the theoretical pattern of basal water drainage for the years 1927, 1947, 1961 and 1997, during which period the glacier was thinning and receding. The theoretical drainage pattern for 1997 compares well, in a broad sense, with the locations of active moulins and the hydraulic connection status of boreholes drilled to the glacier bed. Changes in the basal water-flow pattern over the period 1927–97 that are revealed by the theoretical reconstructions of the subglacial drainage system structure are likely to have resulted from changes in glacier geometry. Concurrent with the retreat and thinning of the glacier, the height of medial moraines increased, probably due to the insulating effect of the debris cover reducing the melt of the underlying ice. This increase of moraine heights has led to the formation of hydraulic barriers at the glacier bed such that water flow has become channelized beneath the ice along drainage axes that parallel the course of the medial moraines on the glacier surface.
The Swiss Glaciers 2015/16 and 2016/17
Bauder, Andreas; Funk, Martin; Huss, Matthias; et al. (2018)
The Swiss Glaciers. Glaciological Report

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Andreas Bauder

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