HR: 0830h
AN: C11C-0848    [PDF]
TI: Flow Dynamics from Elevation Changes on the Malaspina-Seward Glacier System, Alaska-Yukon, using High Resolution Airborne and SRTM InSAR-Derived DEMs
AU: * Muskett, R R
EM: rmuskett@inis.iarc.uaf.edu
AF: International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK 99775-7340 United States
AU: Lingle, C S
EM: clingle@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775-7320 United States
AU: Rabus, B T
EM: brabus@mda.ca
AF: MacDonald Dettwiler, Richmond, British Columbia, V6V 2J3, Canada, Richmond, BC V6V 2J3 Canada
AU: Tangborn, W V
EM: hymetco@centurytel.net
AF: HyMet Inc., Court House Square 19001 Vashon Hwy, Suite 201, Vashon Island, WA 98070 United States
AB: The Malaspina piedmont glacier, with an area of 2400 km$^{2}$ (Post and LaChapelle, 2000), includes the Agassiz and Marvine Glaciers to the west and east, respectively, of the central Seward Lobe. Upper Seward Glacier, mostly in Yukon, Canada, is a broad icefield that forms the main accumulation area of Malaspina Glacier. Mt. Irving nunatak divides Upper Seward into western and eastern halves. Lower Seward Glacier, mostly in Alaska, connects Upper Seward to Malaspina Glacier. The combined Malaspina-Seward glacier system, including all tributaries, has a total area of about 5,000 km$^{2}$ (Molnia, 2001). The glaciers of the Malaspina system are characterized by complex flow dynamics, including quasi-periodic surging and pulsating flow. High-resolution DEMs produced from airborne and spaceborne single-pass X-Band InSAR by Intermap Technologies, Inc. (August 2002) and the German Aerospace Center (from the NASA Shuttle Radar Topography Mission, February 2000), respectively, are used to derive short-term surface elevation changes. An adjustment for systematic error in the SRTM DEM is applied. Snow depth vs. altitude is estimated using the mass balance model of Tangborn (1999) on these glaciers from Sept. 1999 to Feb. 2000, and is used to adjust the SRTM DEM to a late summer 1999 level. During the 3-year 1999 to 2002 time period, the Seward Lobe of Malaspina thinned over its eastern half, while the western half thickened by about 10 $\pm$ 1 m on average. This suggests that the main flow direction has changed from southeast, the direction of a major surge in 1987-88 (A. Post, pers. comm.), to southwest. Surges in alternate directions have been hypothesized by A. Post (pers. comm.) as the cause of the intricately folded moraines on Malaspina Glacier. Marvine Glacier, which surged in 2000 (K. Echelmeyer, pers. comm.), shows thickening in its ablation area of up to 60 $\pm$ 1 m and thinning in its accumulation area of up to 60 $\pm$ 1 m. The 3-year mean surface lowering on Agassiz, Malaspina (Seward Lobe), Lower Seward, Marvine and Hayden Glaciers, including a -3.2 m adjustment of the SRTM heights for systematic error, was about 2.7 $\pm$ 1 m, or 0.9 $\pm$ 0.4 m yr$^{-1}$. References Molnia, B., Glaciers of Alaska, Alaska Geographic, 28 (2), 2001. Post, A., and E. LaChapelle, Glacier Ice, University of Washington Press, Seattle, 2000. Tangborn, W.V., A mass-balance model that uses low-altitude meterological observations and the altitude area of a glacier, Geograf. Ann., 81(A), 753-765, 1999.
DE: 1640 Remote sensing
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2003 Fall Meeting