HR: 0800h
AN: C21B-1108    [Abstracts]
TI: Impact of Accumulation Rate on Firn Properties
AU: * Courville, Z
EM: zozo@dartmouth.edu
AF: Thayer School of Engineering, Dartmouth College 8000 Cummings Hall, Hanover, NH 03755
AU: * Courville, Z
EM: zozo@dartmouth.edu
AF: Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH 03755
AU: Albert, M R
C21B-1108 AF: Thayer School of Engineering, Dartmouth College 8000 Cummings Hall, Hanover, NH 03755
AU: Albert, M R
C21B-1108 AF: Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH 03755
AU: Fahnestock, M
C21B-1108 AF: Center for the Study of Complex Systems, University of New Hampshire, Durham, NH 03824
AU: Cathles, L M
C21B-1108 AF: Department of the Geophysical Sciences, University of Chicago, Chicago, Il 60637
AB: Results from a field campaign in a megadunes region of Eastern Antarctica show the relative impact of temperature and accumulation rate on the physical properties of the firn. Megadunes are surface features caused by varying accumulation patterns. Snow accumulates on the windward face of the "dunes" while the leeward faces experience little to no accumulation. They are not readily apparent when viewed from the ground, with amplitudes of 2-5 meters and wavelengths of 2-5 kilometers. The variation in accumulation rate does appear in photographs and microwave images of the area. AWS stations installed within 2 kilometers of one another show that while the temperature and wind patterns of the sites are nearly the same, the variation in accumulation rate from site to site causes significant changes in the physical properties. Grain size, pore size and permeability are most affected by accumulation, while the density shows little influence. The accumulation rate influences the grain size by determining the length of time the firn is subjected to large surface temperature fluctuations. The variation in firn physical properties caused by accumulation rate differences is evident in microwave signals, which are sensitive to grain size, and in permeability profiles, which are sensitive to a combination of both grain size and pore size. The permeability profile in turn affects gas transport within the firn, making it more susceptible to fast diffusion, windpumping and convective mixing.
DE: 0758 Remote sensing
DE: 0770 Properties
DE: 1827 Glaciology (0736, 0776, 1863)
DE: 4932 Ice cores (0724)
SC: Cryosphere [C]
MN: Fall Meeting 2005