HR: 15:25h
AN: C33A-08    [Abstracts]
TI: Recent Elevation Changes on Bagley Ice Valley, Guyot and Yahtse Glaciers, Alaska, from ICESat Altimetry, Star-3i Airborne, and SRTM Spaceborne DEMs
AU: * Muskett, R R
EM: rmuskett@iarc.uaf.edu
AF: International Arctic Research Center, 930 Koyukuk Dr., PO Box 757340, University of Alaska Fairbanks, Fairbanks, AK 99775-7340 United States
AU: Sauber, J M
EM: Jeanne.M.Sauber-Rosenberg@nasa.gov
AF: Planetary Geodynamics Branch, Mail Code 921, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Lingle, C S
EM: clingle@gi.alaska.edu
AF: Geophysical Institute, 903 Koyukuk Dr., PO Box 757320, University of Alaska Fairbanks, Fairbanks, 99775-7320 United States
AU: Rabus, B T
EM: brabus@mda.ca
AF: McDonald Dettwiler Associates, 13800 Commerce Parkway, Richmond, BC V6V 2J3 Canada
AU: Tangborn, W V
EM: hymetco@centurytel.net
AF: Hymet Inc., Suite 201 Courthouse Square, Vashon, WA 98070 United States
AU: Echelmeyer, K A
EM: kechel@gi.alaska.edu
AF: Geophysical Institute, 903 Koyukuk Dr., PO Box 757320, University of Alaska Fairbanks, Fairbanks, 99775-7320 United States
AB: Three- to 5-year surface elevation changes on Bagley Ice Valley, Guyot and Yahtse Glaciers, in the eastern Chugach and St. Elias Mtns of south-central Alaska, are estimated using ICESat-derived data and digital elevation models (DEMs) derived from interferometric synthetic aperture radar (InSAR) data. The surface elevations of these glaciers are influenced by climatic warming superimposed on surge dynamics (in the case of Bagley Ice Valley) and tidewater glacier dynamics (in the cases of Guyot and Yahtse Glaciers) in this coastal high-precipitation regime. Bagley Ice Valley / Bering Glacier last surged in 1993-95. Guyot and Yahtse Glaciers, as well as the nearby Tyndell Glacier, have experienced massive tidewater retreat during the past century, as well as during recent decades. The ICESat-derived elevation data we employ were acquired in early autumn in both 2003 and 2004. The NASA/NIMA Shuttle Radar Topography Mission (SRTM) DEM that we employ was derived from X-band InSAR data acquired during this 11-22 Feb. 2000 mission and processed by the German Aerospace Center. This DEM was corrected for estimated systematic error, and a mass balance model was employed to account for seasonal snow accumulation. The Star-3i airborne, X-band, InSAR-derived DEM that we employ was acquired 4-13 Sept. 2000 by Intermap Technologies, Inc., and was also processed by them. The ICESat-derived profiles crossing Bagley Ice Valley, differenced with Star-3i DEM elevations, indicate preliminary mean along-profile elevation increases of 5.6 ± 3.4 m at 1315 m altitude, 7.4 ± 2.7 m at 1448 m altitude, 4.7 ± 1.9 m at 1557 m altitude, 1.3 ± 1.4 m at 1774 m altitude, and 2.5 ± 1.5 m at 1781 m altitude. This is qualitatively consistent with the rising surface on Bagley Ice Valley observed by Muskett et al. [2003]. The ICESat-derived profiles crossing Yahtse Glacier, differenced with the SRTM DEM elevations, indicate preliminary mean elevation changes (negative implies decrease) of -0.9 ± 3.5 m at 1562 m altitude, -2.6 ± 2.8 m at 1378 m altitude, 6.1 ± 3.5 m at 1142 m altitude, 1.4 ± 12.1 m at 1232 m altitude, -4.0 ± 4.2 m at 250 m to 1217 m altitude, -1.8 ± 3.3 m at 1200 m altitude, and 8.0 ± 6.4 m at 940 m altitude. One ICESat-derived track-to-DEM comparison on Guyot Glacier indicates a preliminary mean elevation change in the 478 m to 1150 m altitude range of -2.8 ± 14.1 m. Results, including additional comparisons to small-aircraft laser altimeter data, with more fully-corrected for estimated snow and ice accumulation / ablation between acquisitions times, will be presented. [Muskett, R.R., C.S. Lingle, W.V. Tangborn, and B.T. Rabus, Multi-decadal elevation changes on Bagley Ice Valley and Malaspina Glacier, Alaska, GRL, 30 (16), 1857, doi:10.1029/2003GL017707, 2003.]
DE: 0720 Glaciers
DE: 0738 Ice (1863)
DE: 1621 Cryospheric change (0776)
DE: 1827 Glaciology (0736, 0776, 1863)
SC: Cryosphere [C]
MN: Fall Meeting 2005