HR: 0800h
AN: C31B-0326    [Abstracts]
TI: Time/Space Migration of Diurnal Cycles Related to Hydrology and Ice Dynamics: Bench Glacier, Alaska
AU: * Fudge, T
EM: tjfudge@uwyo.edu
AF: Dept. of Geology and Geophysics; Univ. of Wyoming, Dept. 3006; 1000 University Ave., Laramie, WY 82071 United States
AU: Harper, J T
AF: Dept. of Geology Univ. of Montana, 32 Campus Dr. \#1296, Missoula, MT 59812 United States
AU: Humphrey, N F
AF: Dept. of Geology and Geophysics; Univ. of Wyoming, Dept. 3006; 1000 University Ave., Laramie, WY 82071 United States
AU: Pfeffer, W T
AF: INSTAAR Univ. of Colorado, Campus Box 450 , Boulder, CO 80309 United States
AB: We present a time/space analysis of the diurnal fluctuations in basal water pressure, surface velocity, stream discharge, and melt water input along the length of Bench Glacier, Alaska. Basal water pressure was measured in 43 different boreholes and surface velocities were recorded at four locations using differential GPS. The melt water input was computed using a surface energy balance model calibrated to surface ablation measurements. The diurnal fluctuations in basal water pressure were often large (80% of overburden pressure). The surface velocity of Bench Glacier throughout the summer commonly varied from 0.01 to 0.05m/day on a diurnal cycle. Preliminary analysis suggests that basal water pressure and surface velocity, however, did not demonstrate a simple correlation. The time of peak basal water pressure did not occur synchronously at all boreholes, and tended to be slightly later at boreholes higher on the glacier. The time of peak basal water pressure also migrated steadily throughout the first half of the melt season from near mid-night (0:00-2:00) to late afternoon (16:00-18:00), and remained relatively constant for the remainder of the melt season. This suggests that the hydrology system developed during the first half of the melt season to accommodate the melt water input more efficiently.
DE: 1827 Glaciology (1863)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting