Variations in the surface velocity of an alpine cirque glacier

Sanders, J. W.; Cuffey, Kurt M.; MacGregor, K. R.; Kavanaugh, Jeffrey L.; Dow, Christine F.

doi:10.1017/jog.2018.85

Cited by 5 publications

(3 citation statements)

References 49 publications

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“…The Norwegian glaciers investigated by Lewis (1960) and others were smaller and simpler, with straight long profiles and fairly flat surfaces. Sanders et al (2018) do, however, observe basal slip, and probable cavity formation following hot spells and a rainstorm. Entry of rain and meltwater through the bergschrund caused significant accelerations lasting several days.…”

Section: Cirque Erosionmentioning

confidence: 95%

“…This is partially because of their tendency to rotational flow, the effects of bergschrunds facilitating quarrying (see below), their earlier formation and longer persistence than valley glaciers, and their steep gradients that permit continued erosionwhereas trunk glaciers may become less effective once they have enlarged their cross-sections sufficiently to evacuate ice discharge (the 'calibration' effect; Evans, 2013). Sanders et al (2018) do not find rotational flow in their 1 km 2 cirque glacier in the British Columbian Rockies, but it has an S-shaped surface long profile with a comparatively flat (4-8°) reach above a central overdeepening, compared with 20-40°above and below. The Norwegian glaciers investigated by Lewis (1960) and others were smaller and simpler, with straight long profiles and fairly flat surfaces.…”

Section: Cirque Erosionmentioning

confidence: 99%

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Glaciers, rock avalanches and the ‘buzzsaw’ in cirque development: Why mountain cirques are of mainly glacial origin

Evans

2020

Earth Surf Processes Landf

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It has been proposed that most cirques are source‐area depressions of large, deep‐seated rock‐slope failures. Yet the close relation between cirques and climate is convincing evidence of the dominance of glacial erosion, rather than rock‐slope failure, in mountain cirque development and distribution. Cirque floor altitudes have a lower limit that varies with snowfall by 1000 m or more between windward and leeward sides of mountain systems. Glaciation levels and equilibrium line altitudes implied by cirques vary in parallel with those for modern glaciers. Cirques are often found mainly on the poleward or leeward slopes of individual mountain ranges, as are modern small glaciers (because of solar radiation and wind effects on ablation and accumulation). Most rock‐slope failures (RSFs: rock slides, rock avalanches and gravitational deformations) do not involve the deep‐seated rotational movement that would produce a cirque form. Although some deep‐seated RSFs with arcuate head scars may be confused with cirques, identification as a glacial cirque is more confident as the floor is longer, wider and more gently sloping. Some scars from major RSFs may resemble poor or moderately developed cirques, but tend to have steeper floors, to be more scattered and closely related to geology, whereas glacial cirques develop on all rock types. Deep‐seated RSFs high on slopes can be associated with seismic shaking, but cirques develop without relation to seismicity. Degree of cirque development can be related to duration of exposure to glaciation. Often RSFs are found adjacent to cirques, or in glacial transfluences; only a proportion are well situated to develop into glacial cirques. Valley‐head cirques are continued down‐valley by glacial troughs. The ‘overdeepening’ (rock basins with reversed slopes) found in a large minority of cirques is not due to rock avalanching, fluvial or periglacial erosion. The RSF proposal should therefore be rejected in favour of the traditional glacial explanation, without any nivation stage being necessary. Rock‐slope failure is one of several possible ways of initiating hollows for glacier accumulation, as well as an ancillary process of cirque extension or widening through collapse of glacially oversteepened slopes. Headward extension of adjacent cirques on a ridge leads to displacement of the divide, sometimes by 2 km or more, lowering ridge and summit altitudes and producing the ‘glacial buzzsaw’ effect. Where a relatively lower snowline has led to cirque erosion on all sides of a mountain, cirque intersection lowers summits further. The buzzsaw hypothesis is not applicable, however, where remnants of a preglacial summit surface survive. © 2020 John Wiley & Sons, Ltd.

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Section: Cirque Erosionmentioning

confidence: 95%

Section: Cirque Erosionmentioning

confidence: 99%

Glaciers, rock avalanches and the ‘buzzsaw’ in cirque development: Why mountain cirques are of mainly glacial origin

Evans

2020

Earth Surf Processes Landf

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“…Thus, ice flow and subglacial topography affect the shape of the glacier surface. In the case of cirque glaciers that experience strong downwasting, ice flow is strongly altered by negative mass balances, leading to a slowdown of glacier velocities, and by the shape of the subsurface (Dehecq et al, 2019;Sanders et al, 2018). Increasing debris cover, shading effects of surrounding cliffs and the topography are important factors that affect mass turnover and flow dynamics (Cuffey & Paterson, 2010).…”

Section: Glacier Characteristics Climate Change Impacts and Gbo Model...mentioning

confidence: 99%

Testing the performance of ice thickness models to estimate the formation of potential future glacial lakes in Austria

Otto

Prasicek

Binder

et al. 2021

Earth Surf Processes Landf

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The emergence of glacial lakes is a significant consequence of global climate change in high mountain regions. Recent developments in ice thickness modelling combined with high-resolution glacier surface data led to the generation of modelling approaches to simulate the ice-free bedrock topography below current glaciers and to detect potential glacier bed overdeepenings (GBO) that may form into future lakes. We simulated the subglacial topography in the Austrian Alps using two different ice thickness models. Glaciers in the study area differ significantly from glaciers investigated in previous studies on potential future lakes because of their in general small size and location often restricted to cirques. The aim of this study is to estimate the number and location of potential future lakes in Austria. We tested the performance of ice thickness models for modelling of potential future lakes in an environment dominated by mountain glaciers that are under high stress of climate change.Modelling results are compared with lakes that evolved since the modelling periods and with data on subglacial topography derived from geophysical surveys. Results show significant differences in model performance concerning the total ice volume and the number of simulated GBOs. The number and total area of the modelled GBOs is overestimated, compared with the number of lakes that have evolved in the past. Most GBOs are simulated for valley type glaciers, even though most glaciers are mountain types. This does not match with the location of existing glacial lakes that are dominantly found in cirques. We ascertain that this modelling approach performs better on large valley type glaciers and less well on mountain glaciers. Intersecting the modelling runs indicates that up to 42 new lakes may form within 23 glaciers in Austria covering a total area of 2 km 2 .

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Deep Learning Low-cost Photogrammetry for 4D Short-term Glacier Dynamics Monitoring

Ioli,

Dematteis,

Giordan

et al. 2024

PFG

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Short-term monitoring of alpine glaciers is crucial to understand their response to climate change. This paper presents a low-cost multi-camera system tailored for 4D glacier monitoring using deep learning stereo-photogrammetry. Our approach integrates multi-temporal 3D reconstruction from stereo cameras and surface velocity estimation from a monoscopic camera through digital image correlation. To address the challenges posed by wide camera baselines in complex environments, we have integrated state-of-the-art deep learning feature matching algorithms into ICEpy4D, a Python toolkit designed for 4D monitoring (https://github.com/franioli/icepy4d). In a pilot study conducted on the debris-covered Belvedere Glacier (Italian Alps), our stereoscopic setup, with a camera base–height ratio close to one, captured daily images from May to November 2022. Our approach utilized SuperPoint and SuperGlue for feature matching, resulting in a daily 3D reconstruction of the glacier terminus, as traditional SIFT-like feature matching fails in this scenario. Using dense point clouds with decimetric accuracy, we estimated daily ice volume loss and glacier retreat at the terminus. The total ice volume loss was $$63\,000\,\text{m}$$ 63 000 m $${}^{3}$$ 3 and the retreat was $$17.8\,\text{m}$$ 17.8 m . Surface kinematics revealed three times higher surface velocity during the warm season (May–September) than in the fall (September–November). Daily analyses revealed a significant short-term correlation between air temperature, glacier surface velocity and ice ablation, providing insight into the glacier’s response to external forces. The low cost and ease of deployment of the proposed system facilitates replication at other sites for short-term monitoring of glacier dynamics.

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Variations in the surface velocity of an alpine cirque glacier

Cited by 5 publications

References 49 publications

Glaciers, rock avalanches and the ‘buzzsaw’ in cirque development: Why mountain cirques are of mainly glacial origin

Glaciers, rock avalanches and the ‘buzzsaw’ in cirque development: Why mountain cirques are of mainly glacial origin

Testing the performance of ice thickness models to estimate the formation of potential future glacial lakes in Austria

Deep Learning Low-cost Photogrammetry for 4D Short-term Glacier Dynamics Monitoring

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