HR: 0800h
AN: C41C-0211    [Abstracts]
TI: The Stability of Landfast Sea Ice: What Makes it so Fast?
AU: * Mahoney, A
EM: Mahoney@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775-7320 United States
AU: Eicken, H
EM: Eicken@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775-7320 United States
AU: Shapiro, L
EM: Lews@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775-7320 United States
AU: Gaylord, A G
EM: nunatech@usa.net
AF: Nuna Technologies, PO Box 1483, Homer, AK 99603 United States
AU: Cotter, P
EM: pcotter@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775-7320 United States
AU: Robson, K
EM: robson@simpson.edu
AF: Simpson College, 701 North C Street, Indianola, IA 50125 United States
AB: Arctic landfast ice is shaped by a range of complex dynamic and thermodynamic sea ice processes that do not exist in the deep Arctic Ocean. The state of the landfast ice cover at any time depends on the history of conditions earlier in the year. Although thermodynamic processes largely determine the growth of stationary ice, the thickness of level landfast ice at the end of the season depends upon the duration for which the ice cover has been stationary. Here, we present and combine the results of three methods of observing the landfast sea ice in Alaska across different scales and addressing the mechanisms that hold it fast to the coast and determine the duration of its quiescent growth period. At the regional scale, Radarsat Synthetic Aperture Radar (SAR) imagery has been used to delineate the seaward landfast ice edge (SLIE) 31 times through the 2001-02 ice season along the northern Alaskan coast. At this scale, the SLIEs resolve themselves into nodes of stability separating regions of greater variability. At the local scale, a land-based side-looking X-band marine radar has been employed to scan landfast ice within approximately 5 km of Barrow, Alaska every 5 minutes. This high temporal resolution captures ice dynamics during the creation of grounded ridges. These ridges can be built in less than an hour and remain for the entire season, before breaking up and drifting away as swiftly as they arrived. At the highest spatial resolution, a Differential Global Positioning System (DGPS) and an electromagnetic induction device have been combined to measure sea ice elevation and thickness nearly continuously along transects within the land-based radar footprint from the beach at Barrow to the SLIE. By combining these data we investigate the relationship between the location of stable nodes along the SLIE and the local bathymetry and coastal configuration. We also examine the processes responsible for creating the nodes in terms of ice motion and deformation. Finally, we look at the possible role that such nodes can play in stabilizing the surrounding landfast ice.
DE: 9315 Arctic region
DE: 4540 Ice mechanics and air/sea/ice exchange processes
DE: 1640 Remote sensing
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting