Classification of debris-covered glaciers and rock glaciers in the Andes of central Chile

Janke, Jason R.; Bellisario, Antonio; Ferrando, Francisco

doi:10.1016/j.geomorph.2015.03.034

Cited by 128 publications

(116 citation statements)

References 32 publications

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“…In rock glaciers, large ranges of ground electrical resistivities were measured (Figure 5), outlining the coexistence of ice-cored and ice-cemented structures under the several meters thick unfrozen surface layer. The decrease of ice concentration and increase of surface debris layer thickness distinguish rock glaciers from debris-covered glaciers here, as proposed by Janke et al (2015). Finally, ice-free debris areas are present in the frontal and some lateral zones of the studied systems.…”

Section: Internal Structuresupporting

confidence: 77%

“…This also explains the debris concentration increase in the glacier margins. These very small glaciers have, therefore, typical characteristics of buried glaciers (Ackert, 1998;Janke et al, 2015). In rock glaciers, large ranges of ground electrical resistivities were measured (Figure 5), outlining the coexistence of ice-cored and ice-cemented structures under the several meters thick unfrozen surface layer.…”

Section: Internal Structurementioning

confidence: 90%

“…In addition, current and recent surface morphology was analyzed with field observations, old oblique photographs that we collected, and numerous maps and aerial photographs available from the websites of national topographic institutes (map.geo.admin.ch and geoportail.gouv.fr; e.g., Figure 3). However, we considered surface morphology with care because confusion and controversy emerged from morphology-centered approaches and relatively hampered the knowledge construction on the complex landsystems study here (Berthling, 2011;Janke et al, 2015). To simplify the analysis, we tried to identify homogeneous sectors that share the same general ground electrical resistivities, surface dynamics and morphology in each study site.…”

Section: General Approachmentioning

confidence: 99%

“…In contrast to the debris-covered glaciers, they do not have accumulation areas from a glaciological point of view. The ice present below the block surface can have glacial (sedimentary ice) and/or non-glacial (e.g., magmatic ice) origin and its concentration is typically lower than within upslope glacier zones (usually <70%, e.g., Haeberli et al, 2006;Janke et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…The complexity of these associations of ice and debris, their position at the frontier between glaciological and periglacial research and the confusion between debris-covered glaciers and rock glaciers mainly explain their limited consideration in cryospheric sciences (Haeberli, 2005;Berthling et al, 2013;Janke et al, 2015). Consequently, very small debris-covered glaciers associated with rock glaciers are commonly ignored in regional glacier inventories (Pfeffer et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

Bosson

Lambiel

2016

Front. Earth Sci.

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This contribution explores the internal structure of very small debris-covered glacier systems located in permafrost environments and their current dynamical responses to short-term climatic variations. Three systems were investigated with electrical resistivity tomography and dGPS monitoring over a 3-year period. Five distinct sectors are highlighted in each system: firn and bare-ice glacier, debris-covered glacier, heavily debris-covered glacier of low activity, rock glacier and ice-free debris. Decimetric to metric movements, related to ice ablation, internal deformation and basal sliding affect the glacial zones, which are mainly active in summer. Conversely, surface lowering is close to zero (−0.04 m yr −1 ) in the rock glaciers. Here, a constant and slow internal deformation was observed (c. 0.2 m yr −1 ). Thus, these systems are affected by both direct and high magnitude responses and delayed and attenuated responses to climatic variations. This differential evolution appears mainly controlled by (1) the proportion of ice, debris and the presence of water in the ground, and (2) the thickness of the superficial debris layer.

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Section: Internal Structuresupporting

confidence: 77%

Section: Internal Structurementioning

confidence: 90%

Section: General Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

Bosson

Lambiel

2016

Front. Earth Sci.

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Patterns of glacier ablation acrossNorth‐CentralChile: Identifying the limits of empirical melt models under sublimation‐favorable conditions

Ayala

Pellicciotti

MacDonell

et al. 2017

Water Resources Research

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We investigate the energy balance and ablation regimes of glaciers in high‐elevation, dry environments using glaciometeorological data collected on six glaciers in the semiarid Andes of North‐Central Chile (29–34°S, 3127–5324 m). We use a point‐scale physically based energy balance (EB) model and an enhanced Temperature‐Index (ETI) model that calculates melt rates only as a function of air temperature and net shortwave radiation. At all sites, the largest energy inputs are net shortwave and incoming longwave radiation, which are controlled by surface albedo and elevation, respectively. Turbulent fluxes cancel each other out at the lower sites, but as elevation increases, cold, dry and wind‐exposed conditions increase the magnitude of negative latent heat fluxes, associated with large surface sublimation rates. In midsummer (January), ablation rates vary from 67.9 mm w.e. d−1 at the lowest site (∼100% corresponding to melt), to 2.3 mm w.e. d−1 at the highest site (>85% corresponding to surface sublimation). At low‐elevation, low‐albedo, melt‐dominated sites, the ETI model correctly reproduces melt using a large range of possible parameters, but both the performance and parameter transferability decrease with elevation for two main reasons: (i) the air temperature threshold approach for melt onset does not capture the diurnal variability of melt in cold and strong irradiated environments and (ii) energy losses decrease the correlation between melt and net shortwave radiation. We summarize our results by means of an elevation profile of ablation components that can be used as reference in future studies of glacier ablation in the semiarid Andes.

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Highly variable aerodynamic roughness length (z₀) for a hummocky debris‐covered glacier

2017

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The aerodynamic roughness length (z0) is an essential parameter in surface energy balance studies, but few literature values exist for debris‐covered glaciers. We use microtopographic and aerodynamic methods to assess the spatial variability of z0 for Lirung Glacier, Nepal. We apply structure from motion to produce digital elevation models for three nested domains: five 1 m2 plots, a 21,300 m2 surface depression, and the lower 550,000 m2 of the debris‐mantled tongue. Wind and temperature sensor towers were installed in the vicinity of the plots within the surface depression in October 2014. We calculate z0 according to a variety of transect‐based microtopographic parameterizations for each plot, then develop a grid version of the algorithms by aggregating data from all transects. This grid approach is applied to the surface depression digital elevation model to characterize z0 spatial variability. The algorithms reproduce the same variability among transects and plots, but z0 estimates vary by an order of magnitude between algorithms. Across the study depression, results from different algorithms are strongly correlated. Using Monin‐Obukov similarity theory, we derive z0 values from the meteorological data. Using different stability criteria, we derive median values of z0 between 0.03 m and 0.05 m, but with considerable uncertainty due to the glacier's complex topography. Considering estimates from these algorithms, results suggest that z0 varies across Lirung Glacier between ∼0.005 m (gravels) to ∼0.5 m (boulders). Future efforts should assess the importance of such variable z0 values in a distributed energy balance model.

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Classification of debris-covered glaciers and rock glaciers in the Andes of central Chile

Cited by 128 publications

References 32 publications

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

Patterns of glacier ablation acrossNorth‐CentralChile: Identifying the limits of empirical melt models under sublimation‐favorable conditions

Highly variable aerodynamic roughness length (z₀) for a hummocky debris‐covered glacier

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Classification of debris-covered glaciers and rock glaciers in the Andes of central Chile

Cited by 128 publications

References 32 publications

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

Patterns of glacier ablation acrossNorth‐CentralChile: Identifying the limits of empirical melt models under sublimation‐favorable conditions

Highly variable aerodynamic roughness length (z0) for a hummocky debris‐covered glacier

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Highly variable aerodynamic roughness length (z₀) for a hummocky debris‐covered glacier