Publikationsdatum:
2019-07-17
Beschreibung:
Surface elevations from satellite radar altimetry (Geosat, Seasat, and ERS-1) and bedrock topography from airborne radar sounding (Simon Ekholm's Danish compilation) are combined to derive maps of the driving stresses in the Greenland ice sheet. The stress vector, tau = rho g h sin(alpha), is calculated using surface slope vectors, alpha, from surface elevations and ice thicknesses, h, from the difference between surface and basal elevations. Since the 5-km scale of the surface slope is only about 2 times the ice thickness, the stress maps show spatial variations indicative of longitudinal stress gradients associated with topographic undulations. Values of alpha generally vary from near zero at the ice divides to maxima values around 120 kpa, returning to near zero in a narrow band at the edges. The distribution of alpha's peaks at 60 kpa with an approximate sigma of +/- 20 kpa. Areas of very low alpha near the origin of the northeast ice stream may indicate small sub-glacial lakes. The profile of alpha, down the ice stream from near the ice divide, increases to a maximum of about 120 kpa near the margin, which is characteristic of East Antarctic outlet glaciers and in contrast to West Antarctic ice streams where alpha has maximum values 400 to 500 km inland from the grounding lines. Overall distributions of alpha values are compared with those for the Antarctic ice sheet and the Mars Northern ice cap.
Schlagwort(e):
Earth Resources and Remote Sensing
Materialart:
Apr 17, 1999 - Apr 23, 1999; The Hague; Netherlands
Format:
text
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