Driving a high-resolution dynamic ice-sheet model with GCM climate: Ice-sheet initiation at 116 000 BP

David Pollard, Starley L. Thompson

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Most dynamic ice-sheet studies currently use either empirically based parameterizations or simple energy-balance climate models for the surface mass-balance forcing. If three-dimensional global climate models (GCMs) could be used instead, they would greatly improve the potential realism of coupled climate - ice-sheet simulations. However, there are two serious problems in simulating realistic mass balances on ice sheets from GCM simulations: (i) dynamic ice-sheet models and the underlying bedrock topography need horizontal resolution of 50-100 km or less, but the finest practical resolution of atmospheric GCMs is currently ∼250 km, and (ii) GCM surface physics usually neglects the local refreezing of meltwater on ice sheets. Two techniques are described that address these problems: an elevation correction applied to the atmospheric GCM fields interpolated to the ice-sheet grid, and a refreezing correction involving the annual totals of snowfall, rainfall and local melt at each grid-point. As an example of their use, we have used the GENESIS version 2 GCM at 3.75° × 3.75° resolution to simulate the climate at the end of the last interglaciation at ∼116 000 years ago. The atmospheric climate is then used to drive a standard two-dimensional dynamic ice-sheet model for 10 000 years on a 0.5° × 0.5° grid spanning northern North America. The model successfully predicts ice-sheet initiation over the Baffin Island highlands and the Canadian Archipelago, but at a slower rate than observed. A large ice sheet nucleates and grows rapidly over the northwestern Rockies, in conflict with geologic evidence. Possible reasons for these discrepancies are discussed.

Original languageEnglish (US)
JournalAnnals of Glaciology
Volume25
StatePublished - Dec 1 1997

All Science Journal Classification (ASJC) codes

  • Earth-Surface Processes

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