HR: 0800h
AN: C51A-0263    [Abstracts]
TI: Acceleration and retreat of Kangerdluggsuaq glacier, East Greenland from ERS and Envisat SAR feature tracking
AU: * Luckman, A J
EM: A.Luckman@Swansea.ac.uk
AF: School of the Environment and Society, Swansea University, Swansea, SA2 8PP United Kingdom
AU: Murray, T
EM: T.Murray@Swansea.ac.uk
AF: School of the Environment and Society, Swansea University, Swansea, SA2 8PP United Kingdom
AU: Hanna, E
EM: E.Hanna@sheffield.ac.uk
AF: Department of Geography, University of Sheffield, Sheffield, S10 2TN United Kingdom
AB: The recent thinning, retreat and acceleration of Greeland outlet glaciers is of great interest because the processes causing these events are poorly understood. Enhanced surface-melt-induced acceleration may be providing a feedback mechanism which is not currently incorported into modelled predictions of the future mass balance of the ice sheet in a warming climate. Kangerdluggsuaq, in East Greenland, was observed by the NASA Airborne Terrain Mapper to thin by up to 50m between 1993 and 1998, although how sudden this process occurred remained unclear. Velocities in 1996 showed a significant negative mass balance suggesting that dynamic thinning was occurring, and the glacier appeared to have undergone a major acceleration and retreat by 2005 [New Scientist, 2005]. We present an improved history of surface velocities and frontal positions for Kangerdluggsuaq derived using satellite data from ERS between 1992 and 1998 and from Envisat between 2002 and 2005. Surface velocities are determined using feature tracking between 35-day repeat-pass pairs of SAR images. Frontal positions from over 70 images show considerable variability and a major retreat was seen to start during the second half of 2004, proceeding in stages during early 2005. Surface velocities also show more variability than expected with the largest increase occurring during the retreat phase in early 2005. We compare these velocity and frontal changes to modelled surface mass balance data to attempt to assess the causes of the recent acceleration.
DE: 0720 Glaciers
DE: 0730 Ice streams
DE: 0758 Remote sensing
SC: Cryosphere [C]
MN: Fall Meeting 2005