The Glaciation Level and Lowest Equilibrium Line Altitude in the High Canadian Arctic: Maps and Climatic Interpretation

Abstract

The glaciation level (GL) over the Queen Elizabeth Islands is highest over the main mountain areas. There are extremely steep gradients approaching 15 m km^–1 along the northwestern margin of the archipelago where the glaciation level is very low (300 m a.s.l.). Although the glaciation level mirrors topography on a gross scale, at the finer level the relationship breaks down, probably because of the effect of the mountains on precipitation patterns. There appears to be a sharp decline in the elevation of the glaciation level between the Canadian islands and northwest Greenland. The elevation of the lowest equilibrium line altitudes (ELAs) are 100 to 200 m below the GL with a minimum elevation of 200 m a.s.l. The GL represents a theoretical surface where winter net mass accumulation is equalled by summer mass ablation. The two primary controls on the elevation and gradient are, therefore, related to the pattern of winter snow accumulation and summer snowmelt. An analysis of available climatic data (one meteorological station per 100,000 km²) is limited by the sparcity of records and the bias of existing stations to a coastal location. Nevertheless, on the shorter time scale, fluctuations in the height of the July freezing level correlate strongly with changes in glacier ELAs. However, there is little spatial correlation between decadal maps of July freezing levels and either GL or ELA surfaces.