Project Summary
this paper we "calibrated" the model by adjusting basal sliding conditions as well as flow and sliding parameters to obtain a "best fit" to the present ice sheet configuration. Using this as a starting point we then modified the mass balance distribution over the ice sheet to pro...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.55.6372 http://www.umcs.maine.edu/~shamis/papers/pro/whole.ps |
| Summary: | this paper we "calibrated" the model by adjusting basal sliding conditions as well as flow and sliding parameters to obtain a "best fit" to the present ice sheet configuration. Using this as a starting point we then modified the mass balance distribution over the ice sheet to produce "extreme" configurations, both for the maximum and minimum extents. Results presented in this paper agree qualitatively with a similar exercise carried out by Huybrechts [17]. A comparison between the measured surface [6] and the fitted surface is presented in Figures 1a and 1b , with the distribution of the fitting parameter (the sliding fraction, f) shown in Figure 1c . Due to the coarseness of the grid and other uncertainties in the defining data, this distribution can be considered as little more than a "sketch" of the underlying distribution of sliding within the ice sheet. The distribution does agree rather well with traditional expectations for regions of sliding. There is the almost complete dominance of flow throughout the interior of the ice sheet. Sliding only occurs in localized regions around the margin of the ice sheet and in regions known to be associated with ice streams. Figure 2 shows a site map which locates the regions fitted in this fashion. Of primary interest is a large region encompassing Ice Streams A, B, C, D, and E along the Siple Coast. Also fitted is a region around Pine Island and Thwaites Glacier, around Byrd Glacier, around the Amery Ice Shelf, and an ice stream along the Shirase Coast. The grid in all cases has a 20 km spacing between nodal points, in contrast with the 100 km spacing used in the fitting of the entire ice sheet. Figures 3a, b, c, and d show the results of this fitting process for the Pine Island region. Figure 3a shows the calculated and pres. |
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