CGRG Bibliography of Canadian Geomorphology
Search Results
Author : Hachem, S.; Allard, M.; and Duguay, C.
Date : 2007.
Title : Mapping permafrost using land surface temperatures from the moderate resolution imaging spectroradiometer (MODIS).
Publication : ArcticNet 2007 Annual Scientific Meeting. December 11-14, 2007. Collingwood, Ontario.
Issue : Programme.
Page(s) : 17.
Abstract
Permafrost is a climatic phenomenon. Its spatial distribution and its thermal regime depend on surface temperature, freezing indices and thawing indices. So far, the permafrost zones were mapped by interpreting its spatial distribution through sparsely available climatic data supported with some knowledge of the spatial occurrence of diagnostic landforms (e.g polygons, palsas, etc). We report herein the results of a new method giving a much greater spatial resolution (1 km2) to map permafrost. It is the first time that the Land Surface Temperatures (LST) - Near-surface “skin” temperature data - products retrieved by MODIS sensors onboard Aqua and Terra satellites are used to map surface temperatures over Arctic regions. An algorithm that calculates monthly and mean annual near surface temperatures as well as freezing and thawing indices was developed and applied to the retrieved satellite data. Calibration was performed through highly significant correlations between satellite derived data on single pixels and field automatic stations in Alaska and in Nunavik. Surface temperature and thawing index maps for the period 2000-2005 as well as a new permafrost map of Nunavik and Nunatsiavut are presented. Differences with previously published permafrost maps are explained both in term of methodological differences and in term of the impact of recent climate warming. By comparison with existing climate maps based on data from the period 1931-1960, the new surface temperature maps reveal that the territory of the Québec-Labrador peninsula is now significantly warmer. For instance, mapping the 10°C isotherm of the warmest month indicates that thermal conditions normally conducive to tree survival now extend well beyond the actual tree-line. A significant warming took place recently over the Nunavik-Nunatsiavut territory. The impact on permafrost distribution, active layer depths and vegetation are likely important and can be monitored with the new methodology.
Bibliography of Canadian Geomorphology