HR: 0800h
AN: C51B-0288    [Abstracts]
TI: Glaciological Measurements and Tributary-Trunk Interaction in 2004-2005 on Shackleton Glacier, Clemenceau Icefield, Canadian Rocky Mountains
AU: * Jiskoot, H
EM: hester.jiskoot@uleth.ca
AF: Department of Geography University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4 Canada
AU: Caruso, R
C51B-0288 AF: Department of Geography University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4 Canada
AU: Minke, A
C51B-0288 AF: Department of Geography University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4 Canada
AU: Pigeon, K
C51B-0288 AF: Department of Geography University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4 Canada
AB: It is hypothesized that active tributaries that push into their trunk glaciers can obstruct the trunk outflow, which can potentially affect the ice flow dynamics and mass balance of the entire glacier system. However, research into this type of tributary-trunk interaction is scarce. This research was primarily designed to quantify the effects of Shackleton Glacier's active tributary on the flow dynamics and mass balance of its trunk. Shackleton Glacier is an 8km-long outlet of Clemenceau Icefield (313km²), and is situated 30km WNW of the well-known Columbia Icefield in the Canadian Rockies. Due to its inaccessibility, no previous glaciological studies have been performed on any of the Clemenceau Icefield glaciers. In August 2004 and July-August 2005, one longitudinal and two cross transects of velocity and melt stakes were installed in the ablation zone directly upstream of a large and active tributary. In 2005, additional small-scale strain networks were placed over crevasses along the lower cross transect. Crevasse patterns and surface hydrology were also mapped, and surface roughness, air temperature and katabatic wind measurements were taken. Maximum surface velocity was ~12cm/d for both years. Whereas the flow unit obstructed by the tributary had a 50-90% lower velocity than the unobstructed flow units in 2004, this pattern did not transpire in 2005. In both years the stresses in the longitudinal transect, above the tributary-trunk confluence, range from extensive in the upper zone to compressive in the middle and extensive again in the lower zone, while they remain compressive in the lower zone of the obstructed flow unit. Maximum strain rates are in the order of 0.007 day^-1 and occur in the obstructed flow unit. Surface melt at 1900-2000m asl is 1-12cm we/d in mid-July to late August, while the snowline is at 2200m asl on Aug 9 of both years, and 2300m asl on Aug 21, 2004. Katabatic winds are strongest (~30km/h) when the valley temperatures are highest, and, because these winds tend to cool the air column directly above the glacier surface, it appears that maximum melt rates do not occur on days with the highest valley temperatures (>20°C), but rather on somewhat cooler days.
DE: 0720 Glaciers
DE: 0774 Dynamics
DE: 0776 Glaciology (1621, 1827, 1863)
SC: Cryosphere [C]
MN: Fall Meeting 2005