HR: 0800h
AN: C31B-0313    [Abstracts]
TI: Sub-glacier ocean properties and mass balance estimates of Petermann Gletscher's floating tongue in Northwestern Greenland
AU: * Steffen, K
EM: konrad.steffen@colorado.edu
AF: Cooperative Institute for Research in Environmental Science, University of Colorado, CB 216, Boulder, CO 80309 United States
AU: Huff, R D
EM: rhuff@cires.colorado.edu
AF: Cooperative Institute for Research in Environmental Science, University of Colorado, CB 216, Boulder, CO 80309 United States
AU: Cullen, N
EM: cullenn@cires.colorado.edu
AF: Cooperative Institute for Research in Environmental Science, University of Colorado, CB 216, Boulder, CO 80309 United States
AU: Rignot, E
EM: eric.rignot@jpl.nasa.gov
AF: Jet Propulsion Laboratory, Mail Stop 300-235, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Bauder, A
EM: bauder@vaw.baug.ethz.ch
AF: VAW, Swiss Federal Institute of Technology,, ETH Zentrum, Zurich, ZH 8092 Switzerland
AB: Petermann Gletscher is the largest and most influential outlet glacier in central northern Greenland. Located at 81 N, 60 W, it drains an area of 71,580 km2, with a discharge of 12 cubic km of ice per year into the Arctic Ocean. We finished a third field season in spring 2004 collecting in situ data on local climate, ice velocity, ice thickness profiles and bottom melt rates of the floating ice tongue. In addition, water properties (salinity and temperature profiles) in large, channel-like bottom cavities beneath the floating ice tongue were measured. The melt rates in these "channels" are in excess of 10 m/y and probably responsible for most of the mass loss of the Petermann Gletscher. The ocean measurements will be discussed in comparison with other ocean-profile soundings in the region. The bottom topography of the floating ice tongue has been mapped for some regions using surface-based ground penetrating radar at 25 MHz frequency and NASA aircraft radar profiles. A new map showing these under-ice features will be presented. GPS tidal motion has been measured over one lunar cycle at the flex zone and on the free floating ice tongue. These results will be compared to historic measurements made at the beginning of last century. A "worm-like" sheer feature of 80 m in height and several km in length has been studied using differential GPS readings. The mean velocity of the floating tongue ice is 1.08 km/y in that region, whereas the ice along the margin has a 30%-reduced flow speed, resulting in this strange looking sheer feature. Finally, the mass balance of the floating ice tongue will be discussed based on in situ measurements, aircraft profiles, satellite data, and model approximations.
DE: 3360 Remote sensing
DE: 4540 Ice mechanics and air/sea/ice exchange processes
DE: 3309 Climatology (1620)
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting