HR: 14:55h
AN: C13A-06    [Abstracts]
TI: Mapping Antarctic Megadunes and Other Accumulation-related Features on the East Antarctic Plateau
AU: * Fahnestock, M A
EM: mark.fahnestock@unh.edu
AF: Complex Systems Research Center, 236A Morse Hall University of New Hampshire, Durham, NH 03824 United States
AU: Shuman, C
EM: Christopher.A.Shuman@nasa.gov
AF: Cryospheric Sciences Branch, Code 614.1 NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Scambos, T
EM: teds@icehouse.colorado.edu
AF: National Snow and Ice Data Center, CIRES Univ. of Colorado Campus Box 449, Boulder, CO 80309 United States
AU: Albert, M
EM: mary.r.albert@erdc.usace.army.mil
AF: Geophysical Sciences Division, ERDC Cold Regions Research & Engineering Lab 72 Lyme Road, Hanoverq, NH 03755 United States
AU: Haran, T
EM: tharan@nsidc.org
AF: National Snow and Ice Data Center, CIRES Univ. of Colorado Campus Box 449, Boulder, CO 80309 United States
AU: Courville, Z
EM: Zoe.R.Courville@erdc.usace.army.mil
AF: Geophysical Sciences Division, ERDC Cold Regions Research & Engineering Lab 72 Lyme Road, Hanoverq, NH 03755 United States
AU: Bauer, R
EM: bauerr@kryos.colorado.edu
AF: National Snow and Ice Data Center, CIRES Univ. of Colorado Campus Box 449, Boulder, CO 80309 United States
AB: Using both field observations and continent-wide remote sensing data sets, we characterize accumulation-related features on the Plateau, including the extent, variability, and likely formation processes of megadunes. A new 125-meter MODIS-based Mosaic of Antarctica (MOA), coupled with SAR imagery from the Radarsat Antarctic Mapping Mission (RAMP; Jezek,1999) elevation profiles from ICESat, and compilations of mean accumulation (e.g., Vaughan et al., 1999; Davis et al., 2005) form the basis for the remote sensing analysis. Field measurements from ground penetrating radar, automatic weather stations, surface photos, snowpits, and shallow cores in two field seasons (November-December 2002 and January 2004) provide in situ and subsurface information on dune structure and a context for interpretation of fused remote sensing measurements. Antarctic megadunes are linear stripe accumulations of fine-grained, wind-packed snow, forming 2 - 8 meter high, 1-2km wide ridges separated by 2-6 km of near-zero-accumulation `glaze' regions. Glaze surfaces overlie extremely metamorphosed firn, characterized by very coarse recrystallized grains and poorly expressed layering; remote sensing indicates that this type of firn is spatially dominant in a number of areas on the Plateau. Megadunes occur in high-altitude (2000-3500m ASL) low-accumulation (<5cm water-equivalent/year) regions of the East Antarctic plateau, away from ridge crests and dome summits. They comprise a total area of 1.2 million km2, or roughly 20% of the East Antarctic surface (higher than earlier estimates) but are absent (in the present climate) from the West Antarctic or Greeland Ice Sheet surfaces. Ground-penetrating radar profiles coupled with simple models of snow accumulation reveal that the accumulation rate and the surface profile shape in the windward direction are intimately related for megadunes; this relationship is extended to all megadune areas by a comparison of ICESat profiles, the RAMP backscatter intensity, and the MOA surface structure and grain size composite image.
DE: 0726 Ice sheets
DE: 0736 Snow (1827, 1863)
DE: 0758 Remote sensing
DE: 0776 Glaciology (1621, 1827, 1863)
SC: Cryosphere [C]
MN: Fall Meeting 2005