HR: 0800h
AN: C51B-0391    [Abstracts]
TI: Recent Measurements of Ice Flux From Outlet Glaciers of the South Shetlands and Antarctic Peninsula
AU: * Koppes, M
EM: koppes@geog.ubc.ca
AF: Dept. of Geography, 1984 West Mall University of British Columbia, Vancouver, BC V6T 1Z2, Canada
AU: Hallet, B
EM: hallet@u.washington.edu
AF: Dept. Earth & Space Sciences, Box 351310 University of Washington, Seattle, WA 98195, United States
AU: Rignot, E
EM: Eric.Rignot@jpl.nasa.gov
AF: NASA Jet Propulsion Laboratory, Mail Stop 300-319 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Jaffrey, M
EM: jaffrey@usc.edu
AF: Dept. Earth & Space Sciences, Box 351310 University of Washington, Seattle, WA 98195, United States
AB: One of the most significant events in the evolution of the Antarctic climate and cryosphere was the pronounced glacial erosion in the late Cenozoic that led to the considerable depth and landward sloping profile of the continental shelf, affecting both ice sheet dynamics and the oceanographic processes that drive circulation on the shelf. Understanding how changes in glacial conditions during the LGM may have led to enhanced glacial erosion, however, requires us to first identify the factors that control the amount and rate of glacier erosion in Antarctica today. The bays and fjords of the Antarctic Peninsula contain a rich history of climate change recorded both in proxy climate data (e.g., forams, oxygen isotopes) and in sediment accumulation rates that reflect changes in glacial erosion and sediment transfer. Prior studies revealed large variations in the rate of sediment accumulation across the Peninsula, with a general trend of decreasing sedimentation from north to south and west to east, attributed to climate-driven differences in glacier dynamics. Little is known to date, however, about the individual dynamics of the glaciers in these fjords, and the variability in their sediment delivery, particularly as many of them start to accelerate and retreat (Cook et al., 2005; Rignot, 1998; Angelis and Skvarca, 2003). As part of a study concerning the factors controlling rates of glacial erosion and sedimentation across climatic regimes, the cross-sectional area at the ELA of 16 tidewater glaciers in the South Shetland Islands and the western coast of the Antarctic Peninsula were measured in April 2007. The cross-section area of each glacier is then combined with the mean surface velocity, measured remotely using SAR interferometry, to reconstruct the contemporary ice flux through these glacier systems. The study area spans almost 4° of latitude and 8° of mean annual temperature, encompassing both sub-polar and polar regimes, from Maxwell Bay, South Shetland Islands (62°10' S) to Beascochea Bay, Graham Coast (65°31' S). For the sub-polar glaciers (2 of 16), where the ELA was significantly above sea level, the cross-sectional area at the ELA was measured using ice-penetrating radar. Velocity stakes were also measured at the ELA of these glaciers to ground-truth the satellite measurements of surface velocity. For the remaining polar glaciers, whose ELAs are at sea-level, multi-beam swath bathymetry was used from aboard the RV/IB Nathaniel B. Palmer together with estimates of ice cliff heights to determine the cross-sectional area of the calving front. The variability in ice flux across the sub-polar and polar climatic regimes of the western Antarctic Peninsula reported here will be compared to bathymetric data and sediment accumulation rates derived from 210-Pb and 14-C chronology in the adjacent fjords, as they become available, to examine the influence of both climate and ice flux on the rate of glacial erosion and sedimentation, and to infer potential changes in sediment delivery to the shelf as the region warms.
DE: 0720 Glaciers
DE: 0774 Dynamics
DE: 1621 Cryospheric change (0776)
DE: 3022 Marine sediments: processes and transport
DE: 9310 Antarctica (4207)
SC: Cryosphere [C]
MN: 2007 Fall Meeting