HR: 0830h
AN: C11C-0820    [PDF]
TI: Hypsometry of the Greenland Ice Sheet Margin
AU: * Jiskoot, H
EM: hester.jiskoot@uleth.ca
AF: Department of Geography, University of Lethbridge, Lethbridge, AB T1K 3M4 Canada
AU: Marshall, S J
EM: marshals@ucalgary.ca
AF: Department of Geography, University of Calgary, Calgary, AB T2N 1N4 Canada
AB: Ice sheet dynamics and melt are to a large degree dependent on the character of the ice sheet marginal zone. For Greenland this zone is up to about 100 km wide. This important zone is poorly represented in ice sheet models as these typically use a spatial grid with a 20-40 km grid-space. Both computer and data limitations prevent the reduction of the grid spacing, hence other methods have to be developed to represent ice sheet margins. Subgrid hypsometric parameterisation (area:elevation distribution functions) has already been used to resolve a substantial part of the grid resolution problem in ice sheet models for the inception stages. In order to capture topographic, dynamic and mass balance characteristics of the Greenland Ice Sheet peripheral region, we present a subgrid parameterisation of the elevation distribution of the ice sheet marginal zone through hypsometric terrain characterisation. High resolution (5x5km) Digital Elevation Models (DEMs) (Bamber et al., 2001; Scambos and Haran, 2002) of Greenland were used to obtain a topographic characterisation of ice marginal regions. Hypsometric curves of areas of 20x20km were reconstructed from these DEMs for the entire peripheral zone of the Greenland Ice Sheet. On the basis of these curves, specific classes of hypsometric functions were extracted to represent the variety in and homogeneity of ice surface and proglacial terrain topographic characteristics, ice flow dynamics and the type of ice margin (land-based versus calving). This major partitioning of the ice marginal zones into regions with similar dynamic and topographic characteristics, confirms that specific hypsometric functions can be used as subgrid parametrisation in ice sheet models. Since ice sheet models presently poorly represent iceberg calving, special consideration is directed towards a separate treatment of land-based and calving margins. Further, hypsometric parameterisation with added ablation curves (melt quantified per elevation) will not only provide a more accurate portrayal of ice-land distribution and topography of the ice sheet margin, but also disclose the mass balance signal and local response of glaciers to climate trends.
DE: 1824 Geomorphology (1625)
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
DE: 1894 Instruments and techniques
DE: 9315 Arctic region
SC: Cryosphere [C]
MN: 2003 Fall Meeting