Richard S. Williams Jr.
James B. Garvin
1993
<div class="row"><div class="large-10 medium-10 small-12 columns"><div class="description"><div class="abstract" data-abstract-type="normal"><p>Two geodetic airborne laser altimeter (ALA) systems coupled to Global Positioning System receivers acquired submeter-resolution topographic profiles of the lower parts of Breidamerkurjökull and Skeidarárjökull, Iceland, in May 1989 and September 1991 (Skeidarárjökull) and of Jakobshavns Isbræ, Greenland, in April 1992. Maximum measured crevasse depths on Breidamerkurjökull, Skeidarárjökull and Jakobshavns Isbræ were 20.7, 36.1 and 50.2 m, respectively. Crevasse spacings were 43 m (45 crevasses km<span class="sup">−1</span>) for Breidamerkur jökull, 46–51 m (25 crevasses km<span class="sup">−1</span>) for Skeidarárjökull and 20–40 m (lower part) or 50–80 m (upper part) of Jakobshavns Isbræ (27 crevasses km<span class="sup">−1</span>). Surface slopes were ~2.4° for the lower 11 km of Breidamerkurjökull, ~0.8° for the lower 10 km of Skeidarárjökull and 1.55° for the lower 28 km of Jakobshavns Isbræ (with a range of 0.55° for the final 17 km to ~6.3° for a steep central part several km in length). Average longitudinal strain-rate values, estimated by assuming a bulk ice temperature of 0°C and a density of 880 kg m<span class="sup">−3</span>, ranged from 0.12 a<span class="sup">−1</span><span> </span>for Breidamerkurjökull, to 0.63 a<span class="sup">−1</span><span> </span>for Skeidarárjökull; values for Jakobshavns Isbræ fell between 1.3 and 1.7 a<span class="sup">−1</span>. Remote sensing of glacier microtopography by ALA offers a potential new tool for determining crevasse morphology, spatial density and spacing, meter-scale local slopes, long-wavelength gradients and derived strain rates.</p></div></div></div></div>
application/pdf
10.3189/S0260305500013136
en
International Glaciological Society
Geodetic airborne laser altimetry of Breidamerkurjökull and Skeidarárjökull, Iceland, and Jakobshavns Isbræ, West Greenland
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