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Thursday, July 31, 2008

Truffer et al., 2008: Velocity measurements on and near Ilulissat (Jakobshavn) Glacier, Greenland

Geophysical Research Abstracts,
Vol. 10, EGU2008-A-07161, 2008
SRef-ID: 1607-7962/gra/EGU2008-A-07161
EGU General Assembly 2008
© Author(s) 2008


Velocity measurements on and near Ilulissat (Jakobshavn) Glacier, Greenland

M. Truffer (1,2), J. Amundson (1), M. Fahnestock (3), M. Luethi (2), R. Motyka (1),
J. Brown (2)

(1) Geophysical Institute, University of Alaska Fairbanks (, (2) VAW
Glaciology, ETH Zurich, (3) Institute for the Study of Earth, Oceans and Space, University of
New Hampshire

Ilulissat Glacier has been thinning, accelerating and retreating since 1998. Terminus
velocities reached 13 km/yr, essentially doubling the 6-7 km/yr measured between
1985 and 1995 (Joughin et al., 2004). Since the summer of 2006 we have recorded
velocities on and near the glacier using dual frequency GPS receivers, which were
kinematically processed using a nearby GPS base station on bedrock. The 2007 summer
velocities indicate that the lower 25 km of the glacier have reached their maximum
velocity and perhaps even slowed down somewhat. Velocities measured farther
upstream continue to increase. The inland ice on either side of the ice stream shows
increased rates of convergence, even at 50 km from the ice front. Velocities have not
only increased in magnitude since 1985, but they have also changed direction towards
the ice stream, indicating the effect of draw-down from the ice stream acceleration on
the surrounding ice. All targets show events of variable velocity with amplitudes of up
to 10% of the background, but no sudden slip-events could be recorded.

Joughin, I.R., W. Abdalati, and M. Fahnestock. 2004. Large fluctuations in speed on
Greenland’s Jakobshavn Isbræ glacier. Nature, 432, 608-610.

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