HR: 10:20h
AN: C12A-01    [Abstracts]
TI: Simulation of Seasonal Snow-cover and Glacial Inception With GENIE and GLIMMER
AU: * Rutt, I C
EM: i.c.rutt@bristol.ac.uk
AF: School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS United Kingdom
AU: Payne, A J
EM: a.j.payne@bristol.ac.uk
AF: School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS United Kingdom
AU: Lunt, D J
EM: d.j.lunt@bristol.ac.uk
AF: School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS United Kingdom
AU: Valdes, P J
EM: p.j.valdes@bristol.ac.uk
AF: School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS United Kingdom
AB: Glacial inception and seasonal snow-cover variation are difficult to simulate accurately in Earth-system models. Yet their simulation is of great importance if numerical models are to be used to assess the possible future evolution of the cryosphere. In the present study, we focus on the time of the last glacial inception (the Eemian, 115kyr BP) and the present day. We use a high resolution surface mass-balance and ice dynamics model to test the sensitivity of simulated snow and ice cover in North America to solar insolation and the concentration of atmospheric CO2. This is a stringent test of the model, because we expect glacial inception to occur during the Eemian. We use the GENIE Earth-system model framework, run with an intermediate-complexity, fully-dynamical atmosphere (T21, seven levels), a slab ocean and sea-ice model, and a high-resolution regional thermo-mechanical ice-sheet model (GLIMMER). The coupling is achieved via a degree-day method mass-balance scheme with a daily timestep, forced by hourly temperatures and precipitation from the atmospheric model. The ice model performs a lapse-rate correction to account for the high-resolution topography, and returns albedo and topography to the global model daily. The regional model may be configured to run on any number of arbitrary domains simultaneously, and at different resolutions, with the interpolation needed for upscaling and downscaling of model fields being performed automatically. This enables small-scale topography to be captured within the ice model over particular regions of the Earth's surface, without compromising performance unduly. The model is validated against observations of seasonal snow cover in North America. Fully coupled, 2000-year model runs are then used to investigate the sensitivity of glacial inception to atmospheric CO2 concentration and orbital parameters, separately and in combination. The results are presented and interpreted in the light of the characteristics of the model.
DE: 0700 CRYOSPHERE (4540)
DE: 0762 Mass balance (1218, 1223)
DE: 0798 Modeling
DE: 1626 Global climate models (3337, 4928)
DE: 3344 Paleoclimatology (0473, 4900)
SC: Cryosphere [C]
MN: Fall Meeting 2005