Both model representations of the present day are similar, with both showing some differences from the observed geometry, mainly around the margins. Both models over-predict the extent of grounded ice in the Amundsen Sea and the Amery Ice Shelf regions. Ritz et al. (2001) also over-estimate the extent of grounded ice in the Weddell Sea, while both models underestimate the extent of grounded ice in the Ross Sea (Fig. 12.8A, B). Ritz et al. (2001) ascribe the discrepancies between their model and present day observations to the coarse (40 km) grid resolution of their model, as this hinders their ability to reproduce fast flowing ice streams and flow retarding bedrock features. The result is an ice-sheet which covers a similar area but has a 12% larger volume. Overall the present day ice sheet produced by Huybrechts (2002) is a better match to the observations and this is probably due to the higher resolution (20 km) grid cells of that model.
Figure 12.8: Numerical model reconstructions of the present day ice sheet (A, B) and of the Last Glacial Maximum (C, D) by Huybrechts (2002) and Ritz et al. (2001), respectively. Reproduced with permission from Elsevier and the AGU.
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