CGRG Bibliography of Canadian Geomorphology
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Author : Anslow, F.S.; Marshall, S.
Date : 2002.
Title : New parameters for indexed snow and ice melt modelling and implications for the North American deglaciation.
Publication : Annual Meeting of the Canadian Geophysical Union. May 18-21, 2002, Banff, Alberta.
Issue :
Page(s) :
Abstract
A proper energy balance calculation of snow and ice melt is difficult to carry out in ice sheet models, due to the need for detailed meteorological fields (e.g., wind conditions, cloud cover) that are generally uncertain in the past and are too complex and spatially-variable to extract from climate models. Ice sheet models therefore resort to simple positive degree day (PDD) models to parameterize snow and ice melt. However, PDD models have largely been developed and used for studies in Greenland and other Arctic and Subarctic locations where temperatures are relatively low. Since the melt rate response to temperature change is not linear this presents a problem when such models are extended to midlatitude and tropical glaciers whose temperature regimes are more temperate. This work seeks to remedy this situation by introducing new surface melt parameters for an alpine glacier based on temperature as well as global radiation. The subject glacier, the Haig Icefield, SW Alberta, sees large swings in temperature over the course of a year with warm summer temperatures exceeding 20ºC and winter lows dipping below –40ºC, thus providing an excellent contrast to the settings of previous work. Additionally, the melt model will be coupled with a numerical treatment of meltwater percolation and refreezing through the snowpack for further refinement. These additional parameterizations will allow extension not only to glaciers with similar climate settings, but to those in higher latitudes and paleoclimates as well. We apply the new melt model to Laurentide Ice Sheet simulations of the last glacial cycle to test its effect on modelled deglaciation. Insights into the pattern and timing of ice sheet collapse during deglaciation are offered by the geological record, but this has proven difficult to reconcile with the sea level record, which indicates a staged deglaciation characterized by periods of intense meltwater production. In particular, at least 15 m of sea level rise occurred in a period as short as 300 years ca. 14 kyr BP, an event known as meltwater pulse 1A. There is no clear continental signature of this event. Evidence shows the BÆ lling warm period preceding meltwater pulse 1A in a manner suggesting that the warming may have been responsible for its genesis. We suggest that such warming could have accounted for the meltwater seen in melt water pulse 1A.
Bibliography of Canadian Geomorphology