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ASSESSMENT OF A LAND COVER DRIVEN TTOP MODEL FOR MOUNTAIN AND LOWLAND PERMAFROST USING FIELD DATA, SOUTHERN YUKON AND NORTHERN BRITISH COLUMBIA, CANADA
Session: Physical and Numerical Modelling in Cold Regions / Modélisation physique et numérique en régions nordiques
Alexandre Bevington, Ministry of Forests, Lands and Natural Resource Operations (Canada)
Antoni G. Lewkowicz, Department of Geography, University of Ottawa (Canada)
Air, ground surface and top of permafrost temperatures (TTOP) were measured at 55 sites in three areas of Yukon and northern British Columbia in order to explore relationships between climate-permafrost transfer functions and environmental variables and to assess and validate the TTOP model (Smith and Riseborough, 1996, 2002). The strongest factors controlling climate-permafrost transfer functions are elevation and land cover, though slope, aspect, topographic position and surficial geology were also investigated. In 1000 iterations of the model using randomly-generated equally possible scenarios, 64% of the TTOP model predictions were within ±1°C of measured values, a result that is 6% better than applying a uniform 3°C total offset to the mean annual air temperature. A sensitivity analysis confirmed that the TTOP model is most sensitive to changes in the freezing n-factor, thermal conductivity ratio of the ground, and summer air temperatures.
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