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A thermal instability mechanism for glacier surges Hoffman, Joseph Walter

Abstract

A theory of thermal conduction instabilities that could account for many of the properties of surging glaciers is presented. A one-dimensional diffusion equation with advection is solved numerically using a variation of the Crank-Nicholson method. Geothermal and frictional heating are shown to dominate the melting of ice from the base of the glacier, and the water that is formed is assumed to flow in an approximately uniform sheet between glacier and bedrock. The sliding theory developed by Weertman is used to determine the effects of parameters such as geothermal heat flow, basal shear stress, and bedrock roughness on the behavior of surging glaciers. A cyclic evolution of the temperature profile near the bed of a surging glacier is discovered and is thought to be a principal factor in starting the surge and in determining the surge period. Some good correlation with observation is obtained when the theory is applied to models which resemble known surging glaciers. An attempt to predict the future surge behavior of the Rusty Glacier, Yukon (previously known as the "Fox" Glacier) from the temperature data of Classen and Clarke produced uncertain results.

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