HR: 0800h
AN: C51B-0293    [Abstracts]
TI: Modeling Glacial Stagnation With Higher-Order Flow-line Models
AU: * Vacco, D
EM: dvacco@geosc.psu.edu
AF: Penn State Ice and Climate Exploration Center, Department of Geosciences Pennsylvania State University, State College, PA 16802
AU: Alley, R
EM: ralley@geosc.psu.edu
AF: Penn State Ice and Climate Exploration Center, Department of Geosciences Pennsylvania State University, State College, PA 16802
AU: Pollard, D
EM: pollard@essc.psu.edu
AF: Penn State Ice and Climate Exploration Center, Department of Geosciences Pennsylvania State University, State College, PA 16802
AB: Terminus response of glaciers and ice sheets to climate forcing can lead to stagnation or retreat, with implications for contribution to sea-level change and for effects on landforms. When the mass balance of a glacier becomes negative, it returns to equilibrium by losing mass either by retreating or stagnating. Glacial retreat is the process whereby the glacier loses mass as the terminus recedes up-valley, and the glacier remains whole. Stagnation occurs when a mass of ice in the ablation zone becomes detached from the main glacier during a negative mass-balance state. This modeling effort seeks to understand the parameters that control whether a glacier stagnates or retreats during a state of negative mass balance. Valley glaciers have been modeled as 1-d flow-lines, using the shallow ice approximation, and flow-lines including longitudinal stresses. The numerical experiments have been run to constrain the parameter space controlling glacial stagnation. Initial results indicate that bed geometry is a dominant control on glacial retreat. Additionally important parameters are the amount of climate change (temperature, snow rate, and seasonality), basal regime (frozen vs. sliding), and flow-line divergence. Perturbation analysis and scaling also provides insights into the flow system and it's retreat behavior.
DE: 0700 CRYOSPHERE (4540)
SC: Cryosphere [C]
MN: Fall Meeting 2005