HR: 0830h
AN: C11C-0852    [PDF]
TI: High-Resolution Surface Velocity Measurements by Combined GPS and Automated Optical Surveying
AU: * Pfeffer, W T
EM: pfeffer@tintin.colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado, 1560 30th St, Boulder, CO 80303 United States
AU: Lazar, B
EM: brian.lazar@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado, 1560 30th St, Boulder, CO 80303 United States
AU: O'Neel, S
EM: shad@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado, 1560 30th St, Boulder, CO 80303 United States
AU: Walter, F
EM: fabian.walter@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado, 1560 30th St, Boulder, CO 80303 United States
AU: Harper, J T
EM: joelh@uwyo.edu
AF: Department of Geology and Geophysics, University of Wyoming, 16th and Gibbon, Laramie, WY 82070 United States
AU: Humphrey, N F
EM: neil@uwyo.edu
AF: Department of Geology and Geophysics, University of Wyoming, 16th and Gibbon, Laramie, WY 82070 United States
AB: Ongoing glacier dynamics research at Bench Glacier, Alaska requires not only detailed and accurate measurements of surface velocity and velocity gradients, but also a definitive means of distinguishing between surface uplift arising from vertical extension and uplift arising from englacial water storage. Hourly differential GPS measurements at 3 locations over a 1500 m reach of the glacier were combined with half-hourly automated measurements of a network of 24 optical survey targets distributed in a grid covering a 300 x 500 m region within the GPS profile. Data was acquired nearly continuously for an 18 day period on the optical survey grid and for over 4 months on the GPS profile. Resulting target trajectories are combined with additional measurements of vertical strain in a borehole to calculate all three components of surface velocity and their spatial gradients, and allow us to distinguish vertical extension from uplift at the bed. This information will be used with measurements of water pressure and velocity in a network of 24 boreholes to characterize the relationship between basal sliding, water pressure and water storage.
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2003 Fall Meeting