HR: 1340h
AN: C13B-1072    [Abstracts]
TI: A Dynamic View of Subglacial Lakes in a Glaciation/Deglaciation Cycle
AU: * Johnson, J V
EM: johnson@cs.umt.edu
AF: University of Montana Department of Computer Science, Social Science Building The University of Montana, Missoula, MT 59812-5256 United States
AB: Topographic features likely to correspond to subglacial lakes can be identified as pits in the water pressure potential surface. Given an ice sheet, the primary source of uncertainty in this potential surface is due to the effective pressure. To a first approximation effective pressure may be assumed to be zero, allowing the water pressure potential to be determined from ice thickness and bed elevation. Pits are defined as points on a surface lower or equal in height to all neighbors. Well developed and robust algorithms for identification of pits in surfaces can be found in the hydrological literature. Such an algorithm has been adapted to run after each time step of a thermo-mechanically coupled ice sheet model. To investigate the dynamic nature of subglacial lakes a complete glaciation/deglaciation cycle is run. Sub-glacial lakes are identified as regions where there is both basal melting and a pit. The area and depth of the pit in the hydraulic potential field gives an indication of the volume of the lake. In these cycles, a dynamic picture of the emergence, expansion and subsequent loss of subglacial lakes appears. Areas that were likely to have been persistent subglacial lakes during the last ice age are identified, quantified, and mapped. This map will be of use to investigators wishing to explore the geological and biological records of paleo subglacial lakes.
DE: 0520 Data analysis: algorithms and implementation
DE: 0746 Lakes (9345)
DE: 0766 Thermodynamics (1011, 3611, 8411)
DE: 0768 Thermal regime
DE: 0798 Modeling
SC: Cryosphere [C]
MN: Fall Meeting 2005