HR: 0800h
AN: C51A-0266 INVITED     [Abstracts]
TI: Behavior of supraglacial lakes and their role in outlet glacier dynamics and mass balance of the Greenland Ice Sheet
AU: Joughin, I
EM: ian@apl.washington.edu
AF: Polar Science Center, Applied Physics Lab, University of Washington, 1013 NE 40th Street, Seattle, WA 98105 United States
AU: * Das, S B
EM: sdas@whoi.edu
AF: Geology and Geophysics Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 United States
AB: It is well established that seasonal and interannual variations in surface melt water delivery to temperate glacier beds can cause velocity changes. Recent observations from the Greenland Ice Sheet have shown a similar correlation between ice velocity increases and the summer drainage of surface melt water to the bed through thick (~1200 m) cold ice. There is much to be learned concerning the linkages between surface melt and enhanced flow, motivating new research directed towards improving our understanding of this relationship. In order for significant quantities of surface meltwater to reach the Greenland Ice Sheet's bed and enhance flow, two conditions must be met. First, a large enough source of water is needed, which is a function of the surface energy balance. Second, there needs to be a conduit for the water to reach the bed, at times through over 1 km of cold ice. Supraglacial lakes cover much of the Greenland Ice Sheet's bare-ice, superimposed-ice, and percolation facies. These lakes provide a storage area for surface melt water to accumulate. Additionally, lakes provide reservoirs of water that may contribute to the hydrologically-driven fracture that opens moulins, allowing drainage to the bed. As reservoirs that can drain suddenly, lakes also affect the timing and release of surface melt to the bed. Supraglacial lakes are therefore one of the critical links between surface melting and enhanced basal flow, and have the potential to rapidly respond to future climate change. Many outstanding questions remain of where and why lakes form around Greenland, the total melt-water volume stored in these lakes, and their relationship to outlet-glacier drainage basins. We present new results from a study using remote sensing data to investigate the role of Greenland's supraglacial lakes in delivering melt water to the ice sheet's bed and in modulating ice flow on short time scales. We investigate the formation, distribution and dynamics of supraglacial lakes across the Greenland Ice Sheet. We focus on interannual variability in lake systems around the dynamic and climatically sensitive Jakobshavn outlet glacier region, in West Greenland.
DE: 0726 Ice sheets
DE: 0746 Lakes (9345)
DE: 1827 Glaciology (0736, 0776, 1863)
SC: Cryosphere [C]
MN: Fall Meeting 2005