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Velocity change of the Amery Ice Shelf, East Antarctica, during the period 1968-1999

Lookup NU author(s): Professor Matt King


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Historic velocity measurements of Antarctica's ice sheet represent vital baseline values that allow ice flow velocity variations to be observed over multidecadal timescales, such as those due to climate change. Using velocity values derived from geodetic quality measurements made in the 1960s and from more recent GPS and remote sensing studies during the 1990s, we examine the variability of ice flow velocities of the northern Amery Ice Shelf, East Antarctica, over the 30-year period, 1968-1999. The historic ice shelf velocities are reexamined using original field notes and the previous data analyses are shown to be erroneous, yielding positional and velocity errors of up to 4 km and 150 m/yr respectively. Once corrected, these historic measurements are shown to be in close (1-5 m/yr) general agreement with GPS-derived velocities from the 1990s at similar geographical locations, providing one of the first precise constraints on multidecadal ice shelf velocity variations on a large Antarctic ice shelf. Comparison of the terrestrial and GPS velocities with spatially dense velocity measurements from remote sensing imagery reveals a systematic bias in the latter of up to ±30 m/yr, mostly due to propagation of unmodeled vertical ice shelf motion due to tides and atmospheric pressure variations. We therefore excluded the remote sensing velocities from further comparison and suggest caution in the interpretation of similarly derived ice shelf velocities. Velocity differences between the GPS and terrestrial surveys were compared at nine geographical locations suggesting a small (∼2.2 m/yr or ∼0.6%), but statistically significant, slowdown of the ice shelf. Copyright 2007 by the American Geophysical Union.

Publication metadata

Author(s): King MA, Coleman R, Morgan PJ, Hurd RS

Publication type: Article

Publication status: Published

Journal: Journal of Geophysical Research F: Earth Surface

Year: 2007

Volume: 112

Issue: 1

ISSN (print): 0148-0227

ISSN (electronic):

Publisher: American Geophysical Union


DOI: 10.1029/2006JF000609


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