Intermittent ice sheet discharge events in northeastern North America during the last glacial period |
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Authors: | Brian D Papa Lawrence A Mysak Zhaomin Wang |
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Institution: | (1) Earth System Modelling Group, Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, QC, Canada, H3A 2K6 |
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Abstract: | The 3D ice sheet model of Marshall and Clarke, which includes both dynamics and thermodynamics, is used to successfully simulate
millennial-scale oscillations within an ice sheet under steady external forcing. Such internal oscillations are theorized
to be the main cause of quasi-periodic large-scale ice discharges known as Heinrich Events. An analysis of the mechanisms
associated with multi-millennial oscillations of the Laurentide Ice Sheet, including the initiation and termination of sliding
events, is performed. This analysis involves an examination of the various heat sources and sinks that affect the basal ice
temperature, which in turn determines the nature of the ice sheet movement. The ice sheet thickness and surface slope, which
affect the pressure-melting point and strain heating, respectively, are found to be critical for the formation and development
of fast moving ice streams, which lead to large iceberg calving. Although the main provenance for Heinrich Events is thought
to be from Hudson Bay and Hudson Strait, we show that the more northerly regions around Lancaster Strait and Baffin Island
may also be important sources for ice discharges during the last glacial period.
This paper is dedicated to the memory of Gerard C. Bond. |
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