Mass Balance and Thermal Regime of Laika Ice Cap, Coburg Island, N.W.T., Canada

Blatter, Heinz; Kappenberger, Giovanni

doi:10.3189/s0022143000009126

Cited by 25 publications

(33 citation statements)

References 26 publications

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“…In particular, the latent heat released by meltwater refreezing in the percolation zone can largely warm the nearsurface area (e.g. Müller, 1976;Huang et al, 1982;Blatter, 1987;Blatter and Kappenberger, 1988;Gilbert et al, 2014b). The importance of surface thermal boundary condition in controlling the thermal regime of a glacier has been recognized by recent thermomechanical glacier model studies (e.g.…”

Section: Introductionmentioning

confidence: 97%

An investigation of the thermomechanical features of Laohugou Glacier No. 12 on Qilian Shan, western China, using a two-dimensional first-order flow-band ice flow model

et al. 2018

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Abstract. By combining in situ measurements and a twodimensional thermomechanically coupled ice flow model, we investigate the thermomechanical features of the largest valley glacier (Laohugou Glacier No. 12; LHG12) on Qilian Shan located in the arid region of western China. Our model results suggest that LHG12, previously considered as fully cold, is probably polythermal, with a lower temperate ice layer overlain by an upper layer of cold ice over a large region of the ablation area. Modelled ice surface velocities match well with the in situ observations in the east branch (main branch) but clearly underestimate those near the glacier terminus, possibly because the convergent flow is ignored and the basal sliding beneath the confluence area is underestimated. The modelled ice temperatures are in very good agreement with the in situ measurements from a deep borehole (110 m deep) in the upper ablation area. The model results are sensitive to surface thermal boundary conditions, for example surface air temperature and near-surface ice temperature. In this study, we use a Dirichlet surface thermal condition constrained by 20 m borehole temperatures and annual surface air temperatures. Like many other alpine glaciers, strain heating is important in controlling the englacial thermal structure of LHG12. Our transient simulations indicate that the accumulation zone becomes colder during the last two decades as a response to the elevated equilibrium line altitude and the rising summer air temperatures. We suggest that the extent of accumulation basin (the amount of refreezing latent heat from meltwater) of LHG12 has a considerable impact on the englacial thermal status.

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Section: Introductionmentioning

confidence: 97%

An investigation of the thermomechanical features of Laohugou Glacier No. 12 on Qilian Shan, western China, using a two-dimensional first-order flow-band ice flow model

et al. 2018

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“…Despite this fact, there is a lack of data providing detailed experimental evidence of simultaneous measurements of temperature and water content distributions in polythermal glaciers. Many workers have reported temperature profiles with depth for polythermal glaciers in Scandinavia [ Hooke et al , 1983], Canadian Arctic [ Blatter and Kappenberger , 1988], China [ Maohuan , 1990], and Svalbard [ Björnsson et al , 1996], but we are aware of only two polythermal glaciers in which temperature and water content estimates (published with measurement error) have been compared: Bakaninbreen in Svalbard [ Murray et al , 2000a, 2007] and Storglaciären in northern Sweden [ Pettersson et al , 2004]. These studies reported temperature profiles within the ice column but only gave bulk estimates of ϕ w for the temperate ice.…”

Section: Introductionmentioning

confidence: 99%

Vertical distribution of water within the polythermal Storglaciären, Sweden

et al. 2010

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[1] Knowledge of water content and its distribution in polythermal glaciers is required to model their flow and thermal state. However, observations of water content variations with depth in polythermal glaciers are scarce. Water content can be estimated from radio wave speed because they depend on one another. We obtained continuous profiles of radio wave speed variations with depth from zero-offset radar profiles collected in boreholes approximately 80 m deep in the upper ablation area of Storglaciären, northern Sweden. These profiles show that the microcrystalline water system in the temperate ice is relatively homogeneous. The overall hydrothermal structure at this location is composed of a 20 m thick upper layer of cold, water-free ice, underlain by a temperate ice layer whose average water content is 0.6% ± 0.3%. These results are corroborated by surface radar and thermistor measurements, which show that the depth of the cold temperate transition is 21 m and the calculated water content at that transition is 0.6% ± 0.1%. These findings imply that the whole temperate ice layer is from 3 to 4 times softer than the cold ice and, consequently, that realistic ice flow models of polythermal glaciers should include the effect of water content on viscosity.

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“…Polythermal glaciers and ice caps are common at high latitudes, e.g., in the Canadian Arctic [ Blatter , 1987; Blatter and Kappenberger , 1988], in Svalbard [ Jania et al , 1996], or in Scandinavia [ Holmlund and Eriksson , 1989], but can also be found at high altitudes in the Alps [ Haefeli , 1963; Haeberli , 1976]. In ice sheets, temperate zones can be present at the bed.…”

Section: Introductionmentioning

confidence: 99%

Mathematical modeling and numerical simulation of polythermal glaciers

Aschwanden¹,

Blatter²

2009

J. Geophys. Res.

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[1] A mathematical model for polythermal glaciers and ice sheets is presented. The enthalpy balance equation is solved in cold and temperate ice together using an enthalpy gradient method. To obtain a relationship between enthalpy, temperature, and water content, we apply a brine pocket parameterization scheme known from sea ice modeling. The proposed enthalpy formulation offers two advantages: (1) the discontinuity at the cold-temperate transition surface is avoided, and (2) no treatment of the transition as an internal free boundary is required. Fourier's law and Fick-type diffusion are assumed for sensible heat flux in cold ice and latent heat flux in temperate ice, respectively. The method is tested on Storglaciären, northern Sweden. Numerical simulations are carried out with a commercial finite element code. A sensitivity study reveals a wide range of applicability and defines the limits of the method. Realistic temperature and moisture fields are obtained over a large range of parameters.Citation: Aschwanden, A., and H. Blatter (2009), Mathematical modeling and numerical simulation of polythermal glaciers,

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Mass Balance and Thermal Regime of Laika Ice Cap, Coburg Island, N.W.T., Canada

Cited by 25 publications

References 26 publications

An investigation of the thermomechanical features of Laohugou Glacier No. 12 on Qilian Shan, western China, using a two-dimensional first-order flow-band ice flow model

An investigation of the thermomechanical features of Laohugou Glacier No. 12 on Qilian Shan, western China, using a two-dimensional first-order flow-band ice flow model

Vertical distribution of water within the polythermal Storglaciären, Sweden

Mathematical modeling and numerical simulation of polythermal glaciers

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