Search

Supraglacial meltwater lakes trigger ice-shelf break-up and modulate seasonal ice-sheet flow, and are thus agents by which warming is transmitted to the Antarctic and Greenland ice sheets. To characterize supraglacial lake variability we perform a comparative analysis of lake geometry and depth in two distinct regions, one on the pre-collapse (2002) Larsen B ice shelf, Antarctica, and the other in the ablation zone of Paakitsoq, a land-terminating region of the Greenland ice sheet. Compared to Paakitsoq, lakes on the Larsen B ice shelf cover a greater proportion of surface area (5.3% cf. 1%), but are shallower and more uniform in area. Other aspects of lake geometry (e.g. eccentricity, degree of convexity (solidity) and orientation) are relatively similar between the two regions. We attribute the notable difference in lake density and depth between ice-shelf and grounded ice to the fact that ice shelves have flatter surfaces and less distinct drainage basins. Ice shelves also possess more stimuli to small-scale, localized surface elevation variability, due to the various structural features that yield small variations in thickness and which float at different levels by Archimedes' principle. [ABSTRACT FROM AUTHOR]

Reviews the result of the study on the west antarctic ice sheet collapse. Lubricated surges of the Laurentide ice sheet in the Heinrich layers in the North Atlantic; Changes in the modern west antarctic ice sheet; Thinning of the modern ice sheet.

Abstract: Ice-sheet modeling to understand past changes and project future ones remains limited by uncertainties in key parameters as well as by shortage of computational resources. A fast two-dimensional dynamic/thermodynamic flowline ice-sheet model has been developed and benchmarked to complement three-dimensional models by allowing a more-thorough exploration of parameter space. A nonlinear Glen flow law with an exponent equal to 3 is assumed for ice. A diffusion formulation of the continuity equation for mass balance of ice sheets is employed. The ice-sheet model is coupled to an elastic lithosphere/relaxed asthenosphere isostatic bedrock model. Snow and superimposed ice thicknesses are determined using advective continuity equations. These thicknesses are then used in the parameterization of the surface accumulation and ablation rates under specified meteorological conditions constrained by ice- and ocean-core data. Heat-flow continuity is maintained by the time-dependent advection/diffusion equation in the ice and time-dependent diffusion equation in the underlying rock. We conduct the first benchmarking of which we are aware of a 2-D model against the European Ice-Sheet Modeling Initiative''s (EISMINT) Level 2 and Level 3 intercomparison “Greenland” experiments. Appropriate behavior is simulated, with deviations from results of a three-dimensional model that are fully explainable as arising only from the change in dimensionality. Basal temperatures are quite accurate when compared to data and results from 3-D models. [Copyright &y& Elsevier]

Examines the influence of Great Lakes on the dynamics of the southern Laurentide ice sheet in Quebec. Determination of the sediment flux to the morainal bank; Analysis of the perturbations in ice-flow filed; Effects of lobes advancing over a permafrost-free lake bottom.