HR: 0800h
AN: P41B-0940    [Abstracts]
TI: Modelling the Backscatter Response of Different Zones Within a Polar Glacier
AU: * Langley, K
EM: kirstyl@geo.uio.no
AF: University of Oslo, Department of Geosciences, Blindern PO Box 1047, Oslo, no0316 Norway
AU: Meuller, K
P41B-0940 AF: University of Oslo, Department of Geosciences, Blindern PO Box 1047, Oslo, no0316 Norway
AU: Brandt, O
P41B-0940 AF: Norwegian Polar Institute, Post, Tromso, N-9296 Norway
AU: Hamran, E
P41B-0940 AF: University of Oslo, Department of Geosciences, Blindern PO Box 1047, Oslo, no0316 Norway
AB: In order to better quantify the causes of backscatter in glaciers, we model the backscatter response of a polar glacier to C-band GPR imaging. The motivation for such modeling is the need to develop improved algorithms for glacier parameter retrieval from SAR data, including snow facies type, accumulation rate, etc.. These efforts require a better understanding of C-band scattering mechanisms in relation to snow physical processes and determining more accurate quantitive relationships between backscatter and snow physical parameters. Profiling was done on Kongsvegen glacier, northwest Svalbard using a sled-mounted radar towed behind a skidoo. Averaged traces are taken from each of three key zones of the glacier: ablation area; superimposed ice zone; and the firn area. We define a model for each of the areas based on information from ice cores and velocity profiles from CMPs, obtained at the same time as the GPR profiles. Model variables such as air bubble and ice inclusion size, shape, orientation and fractional volume, and interface roughness are varied within limits set by the field observation. Our model builder `modelGPR' allows fast creation of complex subsurface models including multiple rough layers and statistically distributed inhomogeneities. The response of the models to an electromagnetic wave is calculated by the FDTD software GprMax. We calculate the backscatter energy and compare the resultant trace to the measured GPR trace. A systematic trial and error approach is taken to find the best fit between the synthetic scans and the real data. Comparing response due to volume scattering from air bubbles with scattering from rough snow/ice or ice/ice interfaces provides new perspectives for long-term monitoring of polar glaciers.
DE: 9800 GENERAL OR MISCELLANEOUS
SC: Planetary Sciences [P]
MN: Fall Meeting 2005