HR: 0830h
AN: C11C-0829    [PDF]
TI: Glaciers of Larsen B embayment area show marked speed-up since shelf collapse
AU: Scambos, T A
EM: teds@icehouse.colorado.edu
AF: National Snow and Ice Data Center, University of Colorado CIRES 449 UCB, Boulder, CO 80309 United States
AU: * Bohlander, J A
EM: jennb@nsidc.org
AF: National Snow and Ice Data Center, University of Colorado CIRES 449 UCB, Boulder, CO 80309 United States
AB: Satellite images spanning the period before, during, and after the break-up of the Larsen B ice shelf in March, 2002, show a flow speed increase of several glaciers feeding the now-disintegrated shelf area. Further, the rate of speed-up increased in the months after shelf collapse. Landsat 7 band 8 images (15m pixel size) from 27 Jan 2000, 06 Dec 2001, 06 Apr 2002, 18 Dec 2002, and 20 Feb 2003 were used in an image correlation feature-tracking algorithm to gather the ice motion data along flow centerlines. Crane Glacier, a glacier near Caution Point peninsula, and the Hektoria-Green-Evans glacier system all showed evidence of speed-up. Leppard Glacier, feeding into the remaining southern section of the Larsen B shelf, showed no change in speed over the period. Speeds in the lower portions of the Crane Glacier (for example) increased from 1.7 m/day (27 Jan 2000 to 06 Apr 2002) to 3.1 m/day (06 Apr 2002 to 18 Dec 2002) and then 4.1 m/day (18 Dec 2002 to 20 Feb 2003). Leppard Glacier's lower trunk remained at 1.2 m/day through the same period. Errors in flow speeds are no worse than 10% for the shortest time-interval pair, and much better for other pairs, due to excellent image co-registration on stationary rock features flanking the glaciers. Measurements across all image pairs give consistent results. The results imply: that ice shelf removal has a significant, rapid effect on feeder glacier flow; that the removal of the ice shelf directly affects glacier force balance; and that climate-related shelf removal for other shelves fed by larger ice streams will likely result in a rapid speed-up of those glaciers and a change in the mass balance of the adjacent ice sheet.
UR: http://nsidc.org/agdc
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
DE: 5416 Glaciation
DE: 5462 Polar regions
DE: 9310 Antarctica
SC: Cryosphere [C]
MN: 2003 Fall Meeting