ABSTRACT: A study of High Arctic retrogressive thaw slump dynamics, Eureka Sound Lowlands, Ellesmere Island.

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Abstract

High-latitude regions are expected to exhibit a strong response to projected warming trends due to positive feedback systems inherent to the environment. A significant concern is the expansion of thermokarst and the resulting terrain instability and landscape alteration throughout the Arctic. Retrogressive thaw slumps - landforms resulting from the thawing ice-rich permafrost - are a prominent thermokarst feature in polar landscapes and consist of three main structural components: i) a vertical “headwall” of the permafrost active layer; ii) a steeplyinclined ice “headscarp,” and; iii) a low-angle mud pool forming a lobate pattern at its base. Thaw slumps have reportedly been increasing in frequency and extent due to increased coastal erosion and ablation of massive ground ice. Consequently, rates of slump development are expected to increase under projected climate change scenarios. However, the interplay of climatic, geomorphic, and surficial controls makes it difficult to establish projected rates of retreat. Furthermore, spatial variations in diurnal ablation rates and energy balance anomalies complicate the understanding of retrogressive thaw slump process and development. This study investigates thaw slump process in the Eureka area of the Canadian High Arctic. It attempts to identify microclimatic variation in and around a thaw slump and a possible positive feedback for ice ablation and headwall retreat. Two automatic weather stations were strategically placed in the area of the landform: one was located within the slump floor to gather the microclimate, and the other located upslope of the slump to capture the control climate. Additional instrumentation was placed above the ice face in order to define the energy activity at the ablating ice surface. Initial examination of micrometeorological data indicates a unique energy exchange influenced by slump morphology. Morphologic data were also gathered for the site, including headwall retreat, ice face and terrain angles, and ice characterization, in order to describe associated controls on the landform.

Bibliography of Canadian Geomorphology