HR: 11:20h
AN: C21D-05    [PDF]
TI: Channel-Like Bottom Features and High Bottom Melt Rates 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 80309-0216 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 80309-0216 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 80309-0216 United States
AU: Rignot, E
EM: eric@adelie.jpl.nasa.gov
AF: Jet Propulsion Laboratory, Mail Stop 300-235 4800 Oak Grove Drive, Pasadena, CA 91109-8099 United States
AU: Stewart, C
EM: cste@bas.ac.uk
AF: British Antarctic Survey, High Cross Madingley Road, Cambridge,, CB3 0ET, United Kingdom
AU: Jenkins, A
EM: ajen@bas.ac.uk
AF: British Antarctic Survey, High Cross Madingley Road, Cambridge,, CB3 0ET, United Kingdom
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 second field season in spring 2003 collecting in situ data on local climate, ice velocity, strain rates, ice thickness profiles and bottom melt rates of the floating ice tongue. Last years findings have been confirmed that large channels of several hundred meters in depth at the underside of the floating ice tongue are running roughly parallel to the flow direction. We mapped these channels using ground penetrating radar at 25 MHz frequency and multi-phase radar in profiling mode over half of the glacier's width. In addition, NASA airborne laser altimeter data was collected along and cross-glacier for accurate assessment of surface topography. We will present a 3-D model of the floating ice tongue and provide hypothesis of the origin and mechanism that caused these large ice channels at the bottom of the floating ice tongue. Multi-phase radar point measurements revealed interesting results of bottom melt rates, which exceed all previous estimates. It is worth mentioned that the largest bottom melt rates were not found at the grounding line, which is common on ice shelves in the Antarctica. In addition, GPS tidal motion has been measured over one lunar cycle at the flex zone and on the free floating ice tongue and the result will be compared to historic measurements made at the beginning of last century. The surface climate has been recorded by two automatic weather stations over a 12 month period, and the local climate of this remote region will be presented.
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
DE: 1894 Instruments and techniques
DE: 3309 Climatology (1620)
DE: 3360 Remote sensing
SC: Cryosphere [C]
MN: 2003 Fall Meeting