Continuum-mechanical, Anisotropic Flow model for polar ice masses, based on an anisotropic Flow Enhancement factor

A complete theoretical presentation of the Continuum-mechanical, Anisotropic Flow model, based on an anisotropic Flow Enhancement factor (CAFFE model) is given. The CAFFE model is an application of the theory of mixtures with continuous diversity for the case of large polar ice masses in which induced anisotropy occurs. The anisotropic response of the polycrystalline ice is described by a generalization of Glen's flow law, based on a scalar anisotropic enhancement factor. The enhancement factor depends on the orientation mass density, which is closely related to the orientation distribution function and describes the distribution of grain orientations (fabric). Fabric evolution is governed by the orientation mass balance, which depends on four distinct effects, interpreted as local rigid body rotation, grain rotation, rotation recrystallization (polygonization) and grain boundary migration (migration recrystallization), respectively. It is proven that the flow law of the CAFFE model is truly anisotropic despite the collinearity between the stress deviator and stretching tensors.Comment: 22 pages, 5 figure

Radio Echo Sounding on Four Ice Caps in Arctic Canada

An SCR 718 radar altimeter, mounted on a sledge towed by a motor toboggan, was used to measure ice thickness on parts of the Devon Island Ice Cap, the ice cap on northwestern Ellesmere Island, the Meighen Ice Cap, and the southernmost of the four ice caps on western Melville Island. No echoes were received where the ice thickness exceeded about 800 m. Techniques are described and results presented as bedrock contour maps. On Meighen Ice Cap results of soundings with two radars of different frequencies did not differ significantly but showed some discrepancies from the results of a gravity survey

A further comparison of glacier velocities measured by radio-echo and survey methods

A comparison has been mager between ice velocities that were measured by the radio-echo technique and by a survey method on the Devon Island ice cap, Arctic Canada (lat. 75° 23' N., long. 82° 23'W.). Results were 2.58±0.11 ma1 by radar and 2.17±0.20 m a–1 by survey. The discrepancy between the two measurements is within the limits of statistical significance, and the methods are consigerred to give comparable results