HR: 1340h
AN: C23A-1146    [Abstracts]
TI: On the use of a Transient Climate Simulation to Prescribe Mass Balance Conditions for the Modeling of the Northern Hemisphere Ice Sheets Since the LGM
AU: Huybrechts, P
EM: phuybrechts@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Postfach 120161, Bremerhaven, D-27515 Germany
AU: * Zweck, C
EM: czweck@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Postfach 120161, Bremerhaven, D-27515 Germany
AB: For thermomechanically coupled models of northern hemisphere ice sheets climate plays a dominant role in the accurate simulation of post LGM retreat (1). One often uses GCM data to specify the climatic boundary conditions of these models, from which positive degree day formulations determine mass balance changes. It is customary in these models to use LGM to Present Day (PD) climate anomaly time-slices scaled by a GRIP-derived temperature index in a time dependent manner. Implicit in this formulation is that a) the climate over the last glacial cycle can be interpolated between the 'extreme' states of those of the LGM and PD, b) the advance and retreat of the ice sheets was synchronous, and c) the climatic variability suggested by the GRIP ice core can be considered as representative for the entire northern hemisphere. To examine these assumptions we use the earth-system model ECBILT/CLIO in a transient simulation from the LGM to PD. The output from this model is then used as 200 yr resolution climate forcing for the ice sheet model. Compared to model results using GRIP scaled climate anomalies, we find that features such as the timing of the retreat of the southern margins of the ice sheets and the splitting of the Laurentide and Cordilleran are simulated more in accord with the geomorphological observations. (1) Zweck and Huybrechts, 2005 doi:10.1029/2004JD005489
DE: 0726 Ice sheets
DE: 0762 Mass balance (1218, 1223)
DE: 3337 Global climate models (1626, 4928)
DE: 3344 Paleoclimatology (0473, 4900)
SC: Cryosphere [C]
MN: Fall Meeting 2005