1 Spatial Modelling of the Terrestrial Environment - Georeferencial

22 Spatial Modelling of the Terrestrial Environment
-65 o
-50 o
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80 o
75 o
70 o
65 o
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a
Figure 2.5 (a) A planimetric shaded-relief plot of a 1-km digital elevation model of the
Greenland ice sheet, (b) the same as for (a) but for a 5-km DEM of the Antarctic ice sheet
Antarctica with horizontal postings at 200 m, although over the ice sheet the true resolution
of the data is about 4 km (Liu et al., 1999).
2.4.2 Topography from InSAR
InSAR has the capability to provide much higher-resolution topography (∼25 m) than is
possible with conventional SRAs. No ice sheet scale models run at resolutions as fine as
this but force budget models (discussed later) or thermo-mechanical models of individual
glaciers or basins can benefit from DEMs at a finer resolution than is possible from
SRA data. An example of an InSAR-derived DEM for the north-east Greenland ice stream
(NEGIS) is shown in Figure 2.6. It has been draped over a considerably coarser ice sheet
DEM derived from SRA data (Joughin et al., 2001). The higher resolution of the InSAR
data provides information on flow features that are related to longitudinal stress gradients